You can see the list of supported CPUs here:
https://www.asus.com/motherboards-components/motherboards/prime/prime-a520m-k/helpdesk_cpu?model2Nam...
According to that list the latest generation your motherboard supports is the 5000-series, which you already have. You could go for a higher end 5000-series CPU, but depending on prices in your region it might not be worth it, at that point it would be better to get a new motherboard and a newer gen CPU.
What GPU did you get for yourself? Depending on what you have the CPU might not be a problem at all. Honestly, new games in general run quite poorly these last 1-2 years so smaller upgrade might not really make much difference.
Another thing, what kind of memory you have and how much of it? If I recall correctly the 5000-series CPUs could be quite RAM speed dependant, so perhaps a RAM upgrade might help a bit.