Looking for GPU advise. Upgrading from AMD 5600g integrated graphics

Hi, I'm looking for a budget (250-350) upgrade that adds noticeable performance to my son's current AM4-AMD-5600G-integrated graphics. Mostly he plays Fortnite, Minecraft, GTA, but GPU should not be limited to these, of course. He currently is running a 1080p screen, but it should also perform decent with 1440p. What about memory? is 16 GB a minimum or should 8 GB be fine ( even for future 3 years)?

I would prefer a AMD over Nvidia.

Any recommendations, thoughts, or own experiences?

Picture for attention only