To be honest with you, I’ve had the same problem many, many times.
Your best bet is to use scale and offset for your UIs (read more about that on the Developer Hub), or just position/size them based on what device the player is using.
Use UIAspectRatioConstraint with a ratio of AbsoluteSize.X / AbsoluteSize.Y of a parent frame + use all other the UI constraints with scale-based padding. Also, make all UI instances scale-based and avoid offset which is in pixels.