I'd say just try it out and see how you feel. If you feel defeated and discouraged, then that's the end of it :) However, if you feel motivated to get better results, then you'll find the info you want easily (esp. how to solve the problem[s] that tripped you up)

IPSC ( https://ipsc.ksp.sk/ ) used to be my favorite until they stopped organizing it :'( - but you can still play with the problems and see how you would rank :)

I would advise against reading a bunch of materials first before you do your first contest -- a lot of those stuff are niche and probably doesn't feel different from leetcode grinding, so only do as much as you feel motivated to read and practice.

The same as interviewing resources.

this series is a good start:

https://www.youtube.com/watch?v=DKCbsiDBN6c

Do Advent of Code! It's great fun. Invite your friends and colleagues to participate too, and make your own scoreboard.