|This will require enabling an external repository.|
Click the Menu Button (☰) on upper right corner and choose Software Repositories.
Enable "Third Party Software".
Enable "RPM Fusion for Fedora XX - Nonfree - Steam".
Close the window.
Click on the upper left corner (search icon).
Search for Steam and install it.
|Following installation requires you to be online.|
From top row, choose LIBRARY, then if dropdown reads GAMES open and check TOOLS it should now read ALL (or TOOLS).
Scroll down through the list of your available tools software to download until you find the entries for Proton.
Choose Proton version For example: Proton 5.0
Press OK on next prompt.
Open Steam. Click Steam on the menu bar (upper left corner). Click Setting. Click Steam Play. Check Enable Steam Play for supported titles. Chech Enable Steam Play for all other titles and select the Proton version you installed. Press OK Restart Steam
Install available title from the Library menu and play it.
Some external info on games can be found at Proton games.