The freebsd-update command can be used to update a FreeBSD system

https://www.freebsd.org/doc/handbook/updating-upgrading-freebsdupdate.html

freebsd-update 
usage: freebsd-update [options] command … [path] 
Options:
   -b basedir   -- Operate on a system mounted at basedir
                   (default: /)
   -d workdir   -- Store working files in workdir
                   (default: /var/db/freebsd-update/)
   -f conffile  -- Read configuration options from conffile
                   (default: /etc/freebsd-update.conf)
   -k KEY       -- Trust an RSA key with SHA256 hash of KEY
   -r release   -- Target for upgrade (e.g., 6.2-RELEASE)
   -s server    -- Server from which to fetch updates
                   (default: update.FreeBSD.org)
   -t address   -- Mail output of cron command, if any, to address
                   (default: root)
Commands:
   fetch        -- Fetch updates from server
   cron         -- Sleep rand(3600) seconds, fetch updates, and send an
                   email if updates were found
   upgrade      -- Fetch upgrades to FreeBSD version specified via -r option
   install      -- Install downloaded updates or upgrades
   rollback     -- Uninstall most recently installed updates
   IDS          -- Compare the system against an index of "known good" files.

To get the updates do

freebsd-update fetch

Let it run and download the updates, then run

freebsd-update install

Should say it is installing updates. Then done.