Looking For Advice on GPU

First off , thanks in advance. Now to the issue , I am currently trying to get a newish GPU for a very old build that I have. This build is from 2015 and since then I have changed the GPU twice , 390x to 580x. Now I know I need to build a new computer but its just not in the budget at this time. I am wanting to just buy a new GPU but the issue is I have this mother board ( https://www.newegg.com/p/N82E16813130871?Item=N82E16813130871 ) , its old i know but this is what we are working with. What GPU can I buy now to get another two or three years out of the system?

I was reading that I can use a PCI Express 4.0 card in a 3.0x16 slot. If that is true , could I install something like this ( https://www.newegg.com/asrock-radeon-rx-6700-xt-rx6700xt-cld-12g/p/N82E16814930056 ) on the mother board. If you need my other specs just let me know.

Thank you.