Mesh is terrible, don’t fall for it. It can get you at least some connectivity in the extended areas but it won’t be good connectivity.

The only actually good way to extend WiFi is to install access points and run cables to them.

Cables don’t necessarily need to be regular ethernet but that’s usually the best option. MOCA usually also works great. Powerline can be hit or miss, I’d only consider it a last resort and even then wouldn’t expect it to work well.