Chain Leggings were deliberately designed to not be able to be crafted by the player, although some mods, such as BattleTowers, do allow Chain Armor to be included as dungeon loot.
Chainmail, Minecraft PC Wiki
Minecraft Dungeons:Scale Mail – Minecraft Wiki
List of Armor Recipes Wiki Guide - Page 5 of 6
TIL You can craft Chain Armor with Fire : r/Minecraft
How to Summon an Armor Stand with Chain Armor - Wiki Guide
How to make an armor stand in Minecraft - Quora
Leggings – Minecraft Wiki
List of Armor Recipes Wiki Guide - Page 5 of 6
Chainmail armor in Minecraft: Everything players need to know
How to Make Chain Armor in Minecraft: 8 Steps (with Pictures)
Armor – Minecraft Wiki
Trial Chambers – Minecraft Wiki