How to scale UI properly? (AutoScale doesn't help much)

I am currently making a loading screen and I used AutoScale Lite in order to scale it becuase other methods I try just don’t do it.

I added a Constraint to the loading bar at the bottom of the screen and whenever I view the UI on a phone, for example, it is completely messed up.

Here is what it is supposed to look like:
supposed to look like

This is what it looks like on the iPhone XR as an example: