Can I enchant a Trident with Channeling?

You can get channeling from enchant tables, and in your case, you are simply just unlucky.

Channeling is available from enchantment tables, raid drops,^{‌[Bedrock Edition only]} books obtained by fishing, minecart chests, librarian villagers, and from chests found in Overworld non-village structures.

If you want channeling desperately, you can try via other methods such as fishing , by raid drops or by trading.

If this does not answer your question, you can go here to find out more

Hope this would help!