Creating assets without artifacting

A while back, somebody helped me with an arch vis project where I was having some shadow issues after baking the lighting. It happened wherever something was “clipping” through something else, or was at least touching another area. I spent quite a while fixing it, and it looked fantastic! However, looking back on it now, I’ve seen plenty of games where you can see things clipping into other things. You see it especially if you fall through a map or something. How do game designers stop the artifacting from happening when they do something like place a desk on the floor? Do they seriously cut out a hole of the floor plane everywhere that the desk has legs?

Bump. I really need help with this.