I'm SSHing regularly into my Android phone (and it does not need root) for backup purposes. Used various apps for that but settled for years on Termux.
* Install https://f-droid.org/ store
* Install Termux from there
* Install ssh daemon and rsync in Termux with
pkg upgrade
pkg install openssh rsync
* Read manual on https://wiki.termux.com/wiki/Remote_Access#Using_the_SSH_ser... on how to start, configure, stop ssh daemon. In general: The Termux documentation is good!