Smart clothes for 17 year old boy

[Workisntworking]

DS aged 17 has asked for some smart clothes.

He used as an example that we're going out for lunch and he only seems to have very casual clothes. I suspect he also wants to take a girl out.

He wants a proper shirt, nice trousers.

Where do boys of this age buy smart clothes these days?

My foster son likes Next. He is very sporty but over last 18 months has started wanting smarter clothes. He wears black jeans and a shirt with a belt. He wears chinos and a shirt. He has several jackets. He likes the shirts from M&S.

Foster son also has 3 suits. 1 expensive one I bought for his prom and 2 Next ones I picked up on eBay that were cheap but had only been worn once or twice for a wedding then teen had grown out of them. He wears them all.

Uniqlo is really nice for smart-ish clothes.
Next fine for a suit if he needs one but he doesn't want to take a girl out or go for lunch looking like a mini bank manager so somewhere between casual and formal would be better.

DS wears slim fit chinos from Next as smart trousers.

Instead of a shirt, he usually wears a shacket open over a T shirt, e.g. this one:
https://www.next.co.uk/style/su869552/v11249

Disclaimer: DS is not a fashionista. But I think that outfit looks smart enough for most occasions without being too buttoned up.

Id say a polo shirt with nice jeans, dark blue, black, or khaki color, no pockets(no cargo). Shorts the same think of someone going on a yhat. To go one step up, a button up with jeans or khaki pants. The top button undone and or sleeves rolled up makes it slightly more casual. Nice belt, no cloth, a good watch.
Remember colors and patterns play into all of this. (I personally think plain looks nicer, nothing too flashy or vibrant, muted colors or deep tones, this is opinion based)
This would be an outfit I could say for a nice restaurant, a date, church, holiday wear, etc. My son is 13 and enjoys dressing nice.

Chinos and a nice polo or casual shirt sleeved shirt or smart jeans and the above

Zara is great for teenage boys. I have 2 sons and they both love it there

New trainers to keep clean for best, as opposed to everyday knockabouts. Or ankle boots.

Knitted t-shirt. Shirt worn open over a fresh cotton t-shirt, maybe plaid. Slim-cut shirt. Nice quality jumper.

jeans - can be well-worn but no rips or dodgy washes. Plain chinos that fit nicely. Get the length right. Or well-cut formal trousers in an interesting fabric (absolutely nothing that can be mistaken for school trousers).

A decent coat or blazer or smart casual jacket or puffa.

Next, Uniqlo, Zara, even Primark to play with styles and colours before committing to quality basics.

Try a mix of smart and casual to get the right vibe. Footwear and accessories will make or break it.

Wow, thanks for so many replies. Some great ideas here, thank you.