How to disable a player from zooming out?

This can be achieved using the properties of the camera and the player. If you don't want them to zoom out, you can lock their camera at a certain zoom by setting the Min and Max zoom to the same number.

In a LocalScript:

local player = game.Players.LocalPlayer
player.CameraMinZoomDistance = 15
player.CameraMaxZoomDistance = 15

To lock in first person, you would set the camera mode. Also in a LocalScript:

local player = game.Players.LocalPlayer
player.CameraMode = Enum.CameraMode.LockFirstPerson

Hope this helped!