If you have set Youtube restricted mode, which turns on youtube's built-in filter, but you are still finding explicit content, the next best thing you can do is block thumbnails on youtube so that it's hard to find this content. After that, your options are to schedule when Youtube is unblocked to times of day where you are less likely to look for soft content. you might consider testing out https://livingroomapp.com/ to see if it helps in this case. There is a 7 day free trial and it adds in nudity detection / screenshot accountability across all apps on ios.