how prevalent are psychological warfare tactics in everyday life?

Probably way more than you notice. Not so subtle example, but I will say playing "All I Want for Christmas" on a loop is a very effective way to get me to make my purchase and get the fuck out of your store.

Just imagine how bad it is for the employees
- I would dream of Office Spacing that music player.

In personal relationships we usually call them things like "abuse tactics", "manipulation", etc.

Gaslighting gets all the press, but plain bullying is more common. It doesn't have to be a threat of violence: "go along with my whims or I'll create an unpleasant scene" is bullying too.

"You don't get to leave until my needs are satisfied" is another. Heck, I've seen that from car salesmen confronted by a customer who just wants to pay up front for a car, no financing, no extras. After the check was handed over, but before the car was brought out, there suddenly were a bunch of extra forms to say "no, I don't want these expensive extras."

Would you believe it, I am waging psychological warfare against you right now. It's not working, though. I am very bad at this.

Good on you for doing your best!
Or is that just what you want us to think?

Any kind of marketing and advertising is psychological warfare against you. Especially when the topic is political.

Stores buy specifically tailored perfume to encourage people to buy in demand products, it's not even a secret or anything it's s common practice. Some smaller stores do the same but with music playlists.

Another common one I've seen is adverts, which are exactly that and so common that lots of people don't even notice them anymore.

Then of course there's the simpler things, like the design of a website. Well designed websites make the difference between a customer and a passer-by.

I used to run a small business, and we did a great number of things (relative to our business size and industry) in order to facilitate sales. Every touch point was designed to minimize the friction between the guest and them spending money. Both subtle things and obvious things.

The marketing started as soon as one visited the website (tracking pixels and FB for re-marketing ads) or called for info (we would try to capture at least name and email for additional marketing—always with explicit permission: “May we have your email address so we can send you additional periodic information?”). We had phone call flows and maximum hold times (3 mins).

We retained detailed guest notes and information which we would use to tailor their following visits (manually; any kind of automation was beyond our technical ability at the time).

I’d have to spend some time thinking of all the other ways we did things. Most of which we implemented in a Disney Magic sort of way, in the sense that things are just sort of magically happening without the guest being concerned about it.
- And? Did it pay off to put that amount of effort in?

I mean, advertising exists and is pretty pervasive.

Yeah, I think OP may have missed the memo that "psychological warfare" is basically a euphemism for propaganda. No, it's not brainwashing, the existence of that was itself propaganda made up to explain away Americans that said things the government didn't like in Korea.

In marketing we call them persuasion tactics.

Advertising is basically psychological warfare by the rich against the poor, so anyone who isn't taking their online mental hygiene seriously is being constantly subjected to that

Some people do this in their marriages/relationships. From petty things to manipulation, full blown psychological attacks, even physical violence. Some people are narcissists, psychopaths or just hate another or do it to their kids.

Some have a toxic work environment. I know people who had this severe enough to take sick leave and/or quit.

I say it's pretty common in everyday life of lots and lots of people.

I went from hourly call center to on call 24/7 and being the only point of contact.

When my phone notifies me, just any notification, I panic. The phone rings, I panic. Its been over a year since I left.

Yes, its part and parcel to other issues of mental health, but... Man, do you know how often you get notifications? I've turned most off and still some days I'm ready to smash my phone so it will shut up and I can breathe normally.
- I think you replied to the wrong comment.
  
  That being said: Your story doesn't sound healthy at all. Your brain is basically on high alert 24/7. And you already have severe symptoms. Feeling panic on a daily basis isn't normal.
  
  I think you have to find a way to deal with it. Probably the best advice would be to contact an expert. That'd most likely be a therapist. And they know how to deal effectively with things like this. And mental health in general.
  
  My uninformed opinion is: People absolutely need downtime. You can't be on high alert 24/7. Well, you can for quite a while, especially if you're still in your 20s. But you will break down at some point. Try to re-learn this. Start with taking some time off every day to practice. Take this time for yourself. I don't know you. Maybe read a book, meditate, do crochet, listen to an audiobook and most importantly: put that phone away. Turn it off or put it into another room. Learn to calm down and not constantly be close to the brink of the next panic. Even if you only do it for a few minutes every day. It's okay if you start with some small things.
  
  And there gotta be some technical solution to the problem. You can turn off notifications and read your mail and chat messages twice a day like we used to do 15 years ago. Have different alert tones for different apps, so you immediately know what's up. You can even assign individual rintones to your contacts, so you can straightaway hear who's calling and maybe the adrenaline will stay where it is, because you know it's only your sister-in-law. I don't know exact advice for your life. Some solution intended to break that cycle that triggers you and causes the panic attack to develop.

What exactly is your definition of psychological warfare. This question needs parameters otherwise people will claim anything is psychological warfare

In this question I was more specifically referring to the psychological warfare between citizens, in the quest for dominance and control in the social hierarchy present in our societies

Have you looked at your phone recently? That's all that thing is unless you literally don't use it for anything other than calls and texts, and even then, phone manufacturers are constantly constructing their OS to guide you to other functions.

United States police sirens were deliberately chosen to be as anxiety inducing as possible, with psychological research done way back to find the worst sound possible.

It happens online all the time. Obvious paid trolls and bootlickers will purposefully forum slide comments they don't like to derail consensus and stop people organizing.

Not everyone who disagrees with you is a paid troll or boot, nor is it an act of psychological warfare to tell you you're a dangerous idiot.

I recognise your username. Yesterday you were trying to persuade people to organise armed raids on US police stations and to kidnap and murder judges.
- Lol here's one of the bootlickers 😆 And when I called him out on his lies and bullshit and stopped him forum sliding, he got mad. Big mad. He's here trying to cause trouble again spreading more bullshit hoping to cause a shitfight.
  
  This is the kind of dumb psych warfare shit people do on the regular. I would hope he's at least smart enough to get paid for his trouble -- but the truth is people do get mad enough at you on the internet that they'll do dumb shit like follow you from forum to forum to harass you so they can win something.
  
  Why people wouldn't think psych warfare is normal is weird to me.

Grocery stores, hold music, business deals, recruiting...it's all around you.

Do you mean warfare between nations? Or would psychology warfare include marketing cognitive manipulation?

Highly relevant resource https://www.deceptive.design/