First look at this PSU Minimum Requirement Website for GPU Cards. There it will show you which GPU cards Requires a minimum PSU to run your entire computer with the GPU card you have installed: http://www.realhardtechx.com/index_archivos/Page362.htm
You can use the above as a reference only. I suggest you pick a GPU card with less than 600 Watts.
Then go to this website and input your Processor and the GPU card you want to see if either the Processor or the GPU card will be bottle-necked or not: https://pc-builds.com/calculator/
Then input your computer hardware at these gaming sites to see if what you have will be the minimum requirements for the games you want to play:
https://www.systemrequirementslab.com/cyri
https://www.pcgamebenchmark.com/
https://technical.city/en/can-i-run-it
