Tradeoff on game art pixel size

I’m making a 2D strategy mobile game (similar to Clash of Clans layout but different in nature of gameplay) and I’m wondering how people decide on the pixel size of the game art (e.g., height and width of a building to be placed on the map).

Based on my very novice understanding, the higher the pixel size the more memory it will consume when rendering…and of course the lower the pixel size the fuzzier it would become in high resolution device. What do game artists typically use: 64 x 64, 256 x 256, or even higher in photoshop and scale it down in Unity using the pixel to units setting? Thanks very much and apologies if this has been answered before as I couldn’t find it in forum search!

You generally have to decide that for yourself by profiling the game on the target device.

Create big images, adjust compression at import settings. Profile and adjust accordingly.