We have a 3yo and 4yo. Both go to bed at 7.
The 4yo will sleep till she is woken or if she happens to wake stays in bed looking at books till we get her. She is more than happy with her own company like that. She slept through the night from 7 weeks. I know, miracle!
Our 3yo has to be woken on pre school days at 6.30. On non pre school days she wakes us somewhere between 5.30 and 6.00. It’s not even sometimes, it’s every time!