I would like there to be a function for assigning a point for afk players - players go to afk and teleport them to this place until they leave the afk.

What do you want to happen once the player becomes active again?

Just keep them at the AFK point? Teleport them back to their previous location? Teleport them to spawn?

What do you want to happen once the player becomes active again?

Just keep them at the AFK point? Teleport them back to their previous location? Teleport them to spawn?

Keep them at the AFK point while they are AFK, and then return them to their place.

I'd like to claim this issue. Should I draft the interface or would the maintainers do that?

This is out of scope for the basic AFK functionality that EssentialsX offers, and likely will not be implemented anytime soon, if ever. If you'd like this feature, you'll need to use a more advanced AFK plugin.