You may have to recycle enchantments a few times before Channeling comes up, this is where having a Grindstone comes in handy, you can disenchant the Trident and get some XP in the process, but really it is all down to luck. As it is an enchantment, you can get it simply by placing a trident on a full, 15-bookshelf Enchanting Table setup. Once you have got your trident, it’s time to enchant it! You can get Channeling in a few different ways. It is recommended when making a Drowned Farm to make them in rivers, as it’s a smaller radius with quicker spawns. Drowned can be found in all bodies of water, specifically oceans, and rivers.
If you look into how to make a Drowned Farm, this is another way you can even the odds a bit in obtaining a Trident. You can up the odds a bit, though, by using a Looting III enchanted sword when you kill them, which increasing the chance of the Trident being dropped by a further 3%. From there, there is only an 8.5% chance the Drowned will drop the Trident when killed, meaning the odds of obtaining one are extremely low.
Only Drowned holding a Trident can drop a Trident, and, according to the Minecraft wiki, only 15% of drowned in Bedrock Edition (reduced to 6.25% in Java) spawn with a Trident in hand. The only way to get a Trident without using commands or turning on Creative Mode is from a Drowned. Tridents are a non-craftable item in Minecraft and they aren’t found in chests or from Villagers either. Before you can even consider using this enchantment, you first have to obtain a Trident.