I'm trying to apply this Steam Community advice. I don't see "SET LAUNCH OPTIONS"?
There are 2 ways to do this.
Create a shortcut of the executable (it appears you already have one).
Add the option to "Target". In this case, replace
-nointro. If you need to enter more than one option, make sure each option is separated by a whitespace.
Make sure there is a whitespace between the path to the executable, and the option. It is possible the path is wrapped between quote marks ("). This is necessary if the path itself contains whitespaces. In this case, the "Target" would look like this:
"C:\Games\Quake 2 RTX\q2rtx.exe" -option
2. Set Launch Options
If you're launching games directly from Steam or are using shortcuts created by Steam, this is the only option you have. From what I've seen, Steam does not synchronize Launch Options between devices, so there's no other reason to choose this way (besides preference, convenience, habit, etc).