For the games you listed (WoW, Oblivion Remastered, AoE2E), you don’t really need a super high-end card. Your current 2060 SUPER is still solid, so if you do upgrade, something like a 3060 Ti or 4060 would already be more than enough.
The specs that matter most for you are:
VRAM: 8GB is fine, more is future-proofing.
Cooling & size: Make sure it physically fits your case and has decent cooling.
Power draw: Check that your PSU can handle the new GPU.
Clock speed numbers and “slots” can be confusing, but in reality they don’t change much for your use case. The main traps to avoid are: overspending on features you won’t use (like extreme ray tracing power) and ignoring PSU/case compatibility.
So in short: focus on VRAM, efficiency, and fit — no need to get lost in all the other marketing jargon.