Use Anchor behavior for UI objects.
Usually you target one resolution (for example 1280x720) and one aspect ratio (in this case 16:9). You design the entire game for this resolution. On bigger screens everything will be automatically scaled up, on smaller screens - scaled down.
To support different aspect ratios (for example 4:3), you need to use Anchor and make your backgrounds bigger. You might also need to make other adjustments with events, but this depends on the game.
Understood, more thanks. There are still a couple of problems and such a question.
I do not know what it is connected with like a bug. You may have come across this.
I'm talking about starting a game on an iPhone as I make a game for iPhone.
And sometimes it happens that you launch an application and it knocks down the resolution, that is, it opens, say, less than it should be. Then you restart the application and everything is fine.