Find a saddle in dungeon chests, desert temples, nether fortress chests, ancient city chests, or fishing
Trade with a leatherworker villager at higher levels
Loot saddles from chests in structures
Use a saddle on a horse, pig, strider, or camel
Remove a saddle with shears only in Bedrock Edition for some mobs
Crafting a saddle is not available in vanilla Minecraft