We often have to cuddle our daughter to sleep in her bed, as she’ll not fall asleep without us there. Do you have bedding with any characters that he likes? That might help if not.
We recently moved ours over to his new room as baby is 7 months and in the nursery now. We moved everything over from the nursery including his cot, mobile, whale wall decal etc so it’s as familiar as possible and he absolutely loves it! Sleeps great still so I don’t see any reason to change from the cot
If you have the room have both the bed and the cot in there so he can still sleep in the cot for the time being but get used to the bed - we did this with my little boy and did things like reading stories on his bed which led to him having naps on his bed which led to nighttime sleep on his bed! We also have a guard rail on the bed which I think helped feel a bit more secure like his cot but still allows him to get in and out when he wants.
My little one still gets up in the night and crawls in with us but to get her to sleep in her own bed we sit in the room with her and if/when she gets upset we quietly tell her its okay and give her cuddles till she falls asleep, some nights it can take over an hour and is an absolute pain but we've been doing it like this for a couple months now and she stays in her bed longer and longer each night