I think, the best way to find diamonds without breaking 100000 iron pickaxes is to find the "cheese" cave on 0 level and lower. Such cave çan give you more than 15 diamonds.
Made a new world and am full iron, but, I need to find diamonds, any tips?

Caves are the easiest way. The lower you can go, the better your chances of finding diamonds. If you can't find a cave that goes low enough, strip mine at y -54. If you go lower than that, you might end up running into lava, which spawns at y -55 and below.

went through like 3 caves none were deep enough
do you know how to use C-counter to find caves?

in 1.20 it's slightly harder to get netherite items so you might want to play on a different version

in 1.20 it's slightly harder to get netherite items so you might want to play on a different version
bruh

But then I am looking in a mountain
You have to look lower; iron is most common at around y16. The easiest way is to find a cave.

went through like 3 caves none were deep enough
do you know how to use C-counter to find caves?
no
im new so dont judge me