The cron to run is in code/admin/cli/cron.php. That requires php-cli (command line php). So the path in the set up of the cron job ... something like /usr/bin/php ... isn't the php-cli needed.
From ssh logged onto server as root, what does:
which php [ENTER] show?
Use the full path you see above with the -v switch:
If that does not return PHP 7.3.x (cli) you need to find the correct path to the cli of php.
Fun and games search:
find / -name php [ENTER]
You are looking for path that shows php73 in it and ends with /bin/php
Example ... not real ... if find found a path like this:
Then full path for cron.php would be: