You might have read or noticed that there's an option in the settings to enable an SSH server on the phone. This option can be found in Settings -> System -> Secure Shell.
You might also notice that it doesn't work out of the box because the SSH server is not installed by default, and there are no instructions on how to install the server. There is a good security reason for this.
As explained in the corresponding bug report, it is not a good idea to run an SSH server on your phone without additional - manual - security measures. All FuriOS devices use the same username (it's "furios"), and the password for this user is the lockscreen PIN, which is likely a very short number. Automating a hacker attack on such a setup is trivial.
If you are sure you want to run an SSH server on the device nonetheless and be able to conveniently turn it on and off from the Settings page, consider the following things:
Install the openssh-server package
Harden the SSH server configuration
As a bare minimum, disable password authentication ("PasswordAuthentication no" in /etc/ssh/ssd_config) and set up SSH keys for the furios user
Consider changing the server port to something else than port 22 - this is not an actual security measure, but makes life harder for automated login attempts