Will he take a dummy after say 8pm to help go to sleep? Or have you tried keeping him awake for 1.5 hour ish say from 7 until 830 with doing tummy time, looking at high contrast cards, walking around with him talking to him? Or if that doesn't work maybe a bath later in the day?
My baby was similar. Research has told me that babies this young naturally go down later so it's biologically normal and might not be something you can fix quite yet. My baby is 5 months now and she goes to bed much earlier (between 730-830). It just naturally got earlier over time, starting at around 3 months