Set time format to 24 hours at shell prompt
You type in
date
on your linx box and you get
Tue Sep 5 5:08:49 PM CDT 2023
but you want it to read
Tue Sep 5 17:08:49 CDT 2023
To make that happen execute
localectl set-locale LC_TIME="C.UTF-8"
Log off, then log back on for it to take effect
Tested on Fedora 38