So this is something that I came across recently and wanted to share with the community.

1. Create a custom hook shell script
   Navigate to the .git/hooks directory and create a new file named commit-msg-50chars

cd <path-to-repo>/.git/hooks
touch commit-msg
chmod +x commit-msg

2. Next, open the file and add the below script

#!/bin/sh
# git hook to check the length of the commit messages subject line

#reading the commit message
commit_msg_file=$1
commit_msg=$(head -n 1 "$commit_msg_file")

#checking the length
if [ ${#commit_msg} -gt 50 ]; then
  echo "Error: the commit message exceeds 50 chars"
  echo "max allowed chars - 50"
  exit 1
fi