On Linux, macOS, or Windows, we can use ssh -V (uppercase V) to check the OpenSSH version currently installed.
Example 1
Terminal
$ ssh -V
OpenSSH_9.0p1, LibreSSL 3.3.6
Example 2
Terminal
$ ssh -V
OpenSSH_8.4p1 Debian-5+deb11u1, OpenSSL 1.1.1n 15 Mar 2022