Screen time limit per day instead of time slots on Apple devices

I am trying to set screen time limits on my kids phones through my settings but can only set downtime or scheduled downtime for either the whole day or within timeslots. I can also set limits on specific app use but can’t seem to add a screen limit for say example 1 hour 30 mins per day for the whole day. Is this a thing? I’ve managed to do this on my daughters Amazon tablet so a bit disappointing if this can’t be done with apple. Thanks.

[Re-Titled by Moderator]