Help and advice on potty training!

I’ve been back and forth since my son turned 2 to potty train and he’s just not interested. He will wear pants but just weed and poos as normal and he’s happy to change but never tells us when he needs to go. He’s scared of the toilet, I’ve got 2 toilet seats (one normal seat and one with steps). He will sit on the potty but never does anything on it. We’ve tried chocolates, cars and stickers as rewards but nothing seems to be working. Should I be worried or should I leave him to be ready when he’s ready and keep asking him and telling him to use the potty? As my 18 month old is starting to tell me he’s pooed and will go to the potty when I direct him to it and also pulls his nappy off when he’s had a wee. Any advice would be appreciated! Thank you x