don’t bother with flushing, it can create more problems than it solves, unless you have a specific reason to use it, Ie if you took the rocker off and found tar and varnish, which years ago on the old spec oil was possible.
Today if I saw that, id be reluctant to change the oil for fear of upsetting it lol.
But seriously if you want to treat it, change the oil, run till worm, change again, and change oil filter, then set your self an oil and filter schedule to suit your needs, I change oil every 3 month, filter every 6 months with an oil change.