I’ve always added my public key to a remote host’s authorized_keys file manually, but happened across the “ssh-copy-id” command which does that for you.

[lisa@workstation-fedora .ssh]$ ssh-copy-id -o PreferredAuthentications=password -o PubkeyAuthentication=no lisa@fedora123.example.com
The authenticity of host ‘fedora123.example.com (10.1.2.3)’ can’t be established.
ECDSA key fingerprint is SHA256:5EuKd5LNRnx5sHgQNFb6HO6W/p0hQk4pEmShTgj3zyU.
Are you sure you want to continue connecting (yes/no/[fingerprint])? yes
/usr/bin/ssh-copy-id: INFO: attempting to log in with the new key(s), to filter out any that are already installed
/usr/bin/ssh-copy-id: INFO: 1 key(s) remain to be installed — if you are prompted now it is to install the new keys
lisa@fedora123.example.com’s password:

Number of key(s) added: 1

Now try logging into the machine, with: “ssh -o ‘PreferredAuthentications=password’ -o ‘PubkeyAuthentication=no’ ‘lisa@fedora123.example.com'”
and check to make sure that only the key(s) you wanted were added.

Omit the -o options when attempting to log in over the key-based authentication. This, of course, presupposes that you have a public/private key pair. To create one, use ssh-keygen -t rsa -b 2048