Ok what hopefully is not a hot take.
It’s not okay to spank kids. If you think they aren’t old enough to understand being reasoned with, they aren’t old enough to understand why you’re hitting them, and if they’re old enough to understand reason, then just reason with them.
Another example, if you started a new job and made a mistake, would it be acceptable for your boss to hit you? If it’s illegal to do it to an adult, it shouldn’t be used as discipline for a child.