When we first let the kids watch YouTube it was on the main TV with it's own account. We have consistently monitored it and actively prune recommendations while slowly introducing them to the concept of "the algorithm". From secondary school they pretty much need YouTube on their own PC's for homework reasons and it's harder to totally lock down - we use the family link controls to limit it a little but if they tried to get around them they could. The hope is we've at least prepared them a little before they have totally unfettered access to the internet.
We did try YouTube kids a little but it was such a garbage experience we just blocked the app everywhere.
I thought my youngest was all about watching hour long Minecraft playthroughs but really they are quite interested in game mechanics and speed running. They are just a lot more tolerant of watching hours of videos around a particular game.
I don't overly police their content consumption (although we do talk about limiting shorts). The main thing is at the weekend to kick them off the TV after the morning to go and do something more interactive.