4 year old fussy eater

[Harvey19]

My 4 year old has been fussy from about 1.5 years Id say and just seems to be getting worse. Hoped it would be a phase, kept offering foods but he has continued to refuse more and more. My main concern is dinner. He eats cereals, some fruit, couple of sandwich fillings but when it comes to dinner there is not one “normal” dinner he will eat. I keep offering foods on his plate with safe foods but he is not open to trying anything new unless it’s cake/sweet related.
I'm not sure what I’m looking for posting this but just feel like I’m failing and I’d love for him to have a more varied diet so he can enjoy school events, dinner at friends etc he eats no meat and no veg. Dinners at the moment are a piece of fruit, plain pasta or plain rice, cheese or baked beans. That’s about it. I have read to not act bothered and if they don’t eat it then that’s it but he’s quite happy to do that, I’ve not been offering alternatives and he doesn’t seem bothered.
thanks for reading if you got this far!
any success stories from other parents?

Your son won't eat new foods unless you introduce them to him.

My middle daughter was a very picky eater at that age. She could've quite happily lived on chicken nuggets, baked beans and chips if I let her

What I did to get her out of it was to prepare something she liked, and then prepare something new (prioritise fruits and vegs). I'd withhold the "safe" food until she tried the new food so for example:

"For dinner tonight, mummy is having some peas. Try some". And I'd scoop her some on a separate plate and push her nuggets to one side.
"Mummy I want my chicken nuggets"
"I know you want your chicken nuggets, Evie but you've got to try some peas first. If you don't try the peas, you can't have your nuggets".

Tears and tantrums at first but eventually she'd give in and start eating. She would gag at first, but eventually she'd realise they're not so bad after all. I kept doing this with different foods at different times of the day until she eventually got to the point where she actually sought out to try new things

If he's not bothered about alternatives is he following his centiles? Might be time for a fun little measuring session.

Does he have free school meals?

And I'm assuming you've done the regular stuff like only fruit for snacks and upping his exercise?