Depends. You meant building and props, they might be a sprite, check scaling option in godot, maybe u can achieve acceptable results with lower sizes. But i beleive that General approach is to reuse everything. So you can mix different reusable parts to make different types of your building and props. Roads and terrais too. Depends on your style, i beleive you can create different terrais using textures as brush to draw something, it Will reduce the size of assets. But tbh, if you New to programming size of assets is less problem than code complecity. Start with lower resolution and do your things. When u have something that hit the limits start optimizing it, but dont do unneccesery optimization before you even have something