The standard mechanism is not to ssh into containers, but to connect to a container using docker exec. Given a container Id like 3cdb7385c127 you can connect (aka ssh into it) with
docker exec -it 3cdb7385c127 sh
or for a full login shell if you have bash available in container
docker exec -it 3cdb7385c127 bash -l
You can still ssh into a container if you want to, but you would need to have a ssh server installed, configured and running and you would need to have access to the container IP from outside or redirect container’s :22 onto some port on the host.