If you’re using the docker edition, you just change the version in your .env file, run docker-compose down followed by the docker-compose up command you’re always using.
There’s no built-in way to encrypt the database, so if you’re looking for at-rest encryption, I suggest to put the MySQL data directory on an encrypted volume or to configure your MySQL server to use data-at-rest encryption for the tables in the Mattermost database, but please be careful, it needs to be fully transparent to the Mattermost service!