How to make a dyeable armor like the leather one?

You could make all the armors by hand and making a specific crafting for them, otherwise you will need custom code

Only current way to do that is making separate armor sets all together. You will likely never be able to make the armor to be exactly like leather armor as mcreator, as far as I know, has no way of doing tha without making an armor set for each color. (That would mean making several million colored armor sets, which is next to impossible to do without many many people.)

Only other thing I can really say is to learn how to do it through code.