To write a multi-paragraph Git commit message from the command line, use the
-m option multiple times:
git commit -m "Subject" -m "First paragraph" -m "Second paragraph"
The first message is the subject line, and every subsequent one becomes a paragraph:
commit 3c2a65bd0e77bc323b77463ced0feb7c02f3acac Author: Alice <firstname.lastname@example.org> Date: Sat Jul 17 13:05:58 2021 +0200 Subject First paragraph Second paragraph