Gee, I need to change a setting on $APP. Wait, is that a config file in /etc/$app/? Or did they put that in /var/lib/$app/? Huh, can't find the setting I'm looking for there, guess I better check /etc/sysconfig/$app...

Usually, developers are sane and put things in /etc. However, there are a number of very common applications which have configurations strewn all over the place. Bonus points for apps which have even additional configurations in their systemd service files!

Rpm will tell you where installed files are:

rpm -ql <package>