How to change FOV using procedures

Help!

Try giving speed or slowness

Without the effects, I mean. I'm trying to make a pair of binoculars which, when right-clicked, will change FOV really low (which will, in effect, cause the screen to zoom in) and I don't need effects to slow the player while using binoculars.

I am trying to make a magnifying glass in mcreator and i also want to chang the fov

I'm trying to make a sniper rifle and would also like to know how to change the FOV of a player while holding an item

I don't think this is possible yet.

I wanna do this too.

I too would liek t0 du tis, hlpp

With all seriousness, the best way I found is to add a potion effect without particles, make it go forever while also adding a custom NBT tag saying "scoped" or "zoomed", and when clicked again it will remove the effect and tag, should also make it where the player can't switch away from the item when scoped/zoomed, or make a tick that detects when they switch and then remove the effect and tag if it detects it.

Another fix is to detect if the player already has the effect when scoping, this way the player can't just scope and unscope when they want to remove a slowness effect.

This is the best possible solution I could find.

It's possible to change FOV but you need to code it yourself.

What code would I use? I'm fine with using code as long as it's not too complicated.