I think lots of children go through a stage of objecting to certain clothing but this can be managed with normal behaviour management techniques, the child realises that they stop feeling the offending item a few minutes into wearing it and they pretty much give up complaining.
There are some children whose sensory processing isn't quite what it should be. These are often children who are on the Autism Spectrum but for some this is their only difficulty.
This second group of children don't stop feeling the clothing after a few minutes of wearing it. The sensation continues without reducing or even increases and it becomes overwhelming. The child becomes unable to think about anything else and they are overcome with panic and anger. For these children the normal behaviour management techniques won't work because nothing they are threatened with is worth the torture of wearing the clothing.
My DDs both have AS and have this hypersensitivity at different intensities and so do I to some extent. If I wear certain fabrics or a layer of clothing which is too tight, especially on my arms I get really snappy and bad tempered. When I realise it is the clothing and get changed the relief is overwhelming.
My DD2 (9) rips clothes off like they are burning her sometimes and no amount of bribery or punishment would ever entice her to keep them on for one second longer.
I have learned to let her make her own decisions. Sometimes she would rather have the sensation of being cold than the sensation of wearing the coat. When her anxiety levels are high her sensory processing difficulties become worse and she can only tolerate well used comfortable fabrics, seamless socks and certain cuffs. That can make for an eccentric look but it is better than the alternative.
I cut labels out of clothes, buy seamless socks and iron them, by t-shirts from the Sensory Smart Store, mend trousers with holes in, buy two or three extras of clothing which turns out to be comfortable and I have occasionally had to fight to get her school to allow her to wear an adapted uniform which included a sweatshirt in a different style but same colour as the school uniform. Sometimes if she can't wear clothes appropriate to an occasion and it is a problem we just don't go.
We have to plan extra time to allow for putting gloves, coats, boots etc on and off several times to make sure they are on right too.
My DD1 (15) struggles to wear her High School uniform. I have cut the collar and front out of her blouse and sewn it into her jumper to make it all one layer and she has special permission to wear a tied tie rather than the clip-ons all the other pupils wear.
Get your DS to practise wearing his uniform over the summer. If he really can't tolerate it talk to the school and find a compromise. DD2 couldn't tolerate the normal school trouser fabric. She wore black jeans until M&S started making cotton school trousers. It was more important that she was in school and able to learn than that she was wearing the uniform.
Do your best, look for compromises and try very hard to keep calm. It is really hard to do that last one and I don't always succeed.
HTH