Keep in mind that the post you are replying to is from a bit more than a year ago, so possibly not as common as you think. Just as another data point, I’ve had Rokus (though not Roku TVs) since 2017 and have never had a freeze.
For a quick reset, you can go to Settings -> System -> Power -> System Restart to reboot but that won’t work if it’s frozen. Roku players have a reset button on the bottom or back. I would guess that TVs might as well.
If you want to turn it off often, you might want to plug it into a power strip or extension cord with a switch. I recently bought my parents an extension cord with a big foot switch that is very handy.
Are all TVs the same brand? Is there some specific sequence that leads to the freeze, such as watching some specific channel? I’m wondering if they are truly frozen, or if maybe they just appear to be because the remotes have stopped working? Do you know whether you have Wi-Fi (voice) remotes or IR (simple) remotes?
Banned but back. Because why not?