syspatch helps provide binary patches to OpenBSD. Simply run:

$ doas syspatch

This process can be automated by setting up a cronjob:

$ doas crontab -e
0      *      *       *       *       sleep $((RANDOM % 43200)) && /usr/sbin/syspatch

Notice that a random sleep has been inserted to ensure that the update starts at a unique time. This is designed to prevent all machines from running the exact same job at the exact same time, which would cause performance issues.