Help with scaling for different phone sizes

rlcustoms

I've developed my first small tabbed application in C#. I am not writing XAML. The issue I am having is the scaling between different device types, such as an iPhone 8 and Xr.
The app functions properly, just all my controls are in the wrong places. How do I go able placing a control such as a label in the proper location on both screens. I haven't been able to find any good tutorials on this.

Thanks for they help to a newbie.