From what I can tell, Ukraine's strategy is to heavily degrade Russian artillery, attack logistics, and keep up constant pressure on the front line with small attacks everywhere. If they can stretch out Russia's resources sufficiently, the small attacks will continually gain ground that Russia is unable to recover. If Ukraine is able to push about 20km closer to the Azov Sea, they will have long-range fire-control over the land bridge into Crimea and south-west occupied Ukraine, allowing Ukraine to siege the entire pair of regions.