Pix: christ what did y'all give him?
Nya: a hyperfixation
Pix: yeah that would do it

Jay: I don't understand anything you're saying
Pixal: you haven't closed your eyes in 30 hours
Jay: not true I've-
Pix: blinked I know you've mentioned it five times already
Jay: have I?

Pix: we do have google you guys could just-
Jay: Google's haunted by the spirit of our dead enemy
Pix: yeah well I'm alive and on the fence about all this bullshit
Nya: wait! you gotta explain what grayace means before you decide to kill us
Pix: for you, of course
Jay: what about me
Pix: go to sleep

Nya: wait hold up there's a word for that?
Jay: what do you mean other people are like this
Pix: how is it that you know about the temple of light but not the ace and aro spectrums
Jaya: wasn't in any Wu lessons
Pix: I need to have a word with this guy. fuckin christ

if 16 is the end of school for them, they travel to learn from other blacksmiths before Kai joins the ninja while Nya runs the shop. this also explains Nya's familiarity with armor and Kai's with swords given the low volume of those items that sell. we should see the village that raised them. 3/3

a nearby blacksmith takes them on as apprentices. everyone buys their wonky hooks, spoons, and forks. as their hammer strikes become more confident and alloys sturdier, the knives and chains they make begin to surpass their teacher's.
the local schoolhouse never approaches them about tuition. 2/3

using this logic and some hc, I'm guessing that his temp outfit post-ageup and pre-shopping was:

black hoodie, blue (Nya's favorite color) sneakers, some cheesy graphic shirt from Kai, jeans from Jay, and assumedly spare underclothes everyone chipped in (probably Zane since, y'know, robot)

again, using the most common hc heights (Lloyd being short comparable to Jay, and Kai); Jay and Kai might've given him some pants and a shirt; Cole's hoodie would've been too big on him; assuming he has rather small feet at the time, Nya's feet would've probably been a comparable size

Cole frequently wears black and my brain is telling me he wore a black hoodie at some point, so it's not a stretch to say that Lloyd would've preferred it post-ageup.

he would've needed new shoes, too, and based off of general height hcs he probably had to borrow some of Nya's or Kai's old sneakers

moving into more HC territory than an assessment of the show- we know that his old outfit as a kid was all black with some purple and a green 5 (nice foreshadowing guys) so he likely tried to wear black and a hoodie again. later, he wears more casual green (ofc) so we know this didn't last too long

in typical fashion for a kid with a school uniform background (and as a children's cartoon character), he probably found one or two outfits he liked after aging up and just bought duplicates.

HOWEVER first he would've had to borrow clothes from the boys- it could've been based on their old clothes