Trousers with adjustable waist for wedding for skinny teen

[PotassiumPermanganate]

I've bought my 14yo ds a pair of 30 waist trousers to wear to a wedding this weekend and they are massive 😖 He wears school trousers with the adjustable waist elastic things, so do these exist in men's sizes, or older kids sizes, and if so which shop do I need to go to?

Next do a lot of boys trousers with adjustable waist in both forml (School) styles and chinos).

M&S used to do formal wedding wear in their boys range. IS there nothing in their school range suitable?

Up until very recently my son (now aged 22) was a 28 inch waist. Lots of brands do that size.

I've just spotted the Next chinos so have ordered a couple of pairs. It's not an overly formal wedding so should be ok. Thanks for the tip!

What is his waist measurement?

I've never measured, I just pull the waist adjusters in, but maybe 26?