Need help with scale outer settings

I have a question but can't find an answer anywhere. I would like my game to be fully displayed on all android devices. for this I choose scale outer. when testing on my oppo find x2 pro I see a white border on the right side. I can fix this by making my backround 10% bigger on the right side.

But will that apply on all other devices with other screen sizes for example with tablet etc.

Or is there a chance that on another device the bottom of screen will be white? insead of the right side.

I've already read this guide

construct.net/en/tutorials/supporting-multiple-screen-17

But couldn't find an answer to my question

In short, I want my game to be fully displayed on as many devices as possible (so no black borders) What is the best setting for scale outer or what do do in event sheet to solve this issue?

21:9 is likely the widest aspect ratio you will encounter (minus any multi monitor shenanigans) while 4:3 is the squarest.

To deal with it, you can either use scale outer by setting your viewport to a 4:3 resolution, and design with the consideration that up to 1.75 times that width might be viewable to any given user, or you can use scale inner by setting your viewport to a 21:9 ratio and design with the consideration that a user might have 25% of each side of the screen cut off.

Thank you oosyrag, anyone other ideas?

something like this ? construct.net/en/game-assets/game-templates/pixel-perfect-resolution-554

Thank you all. I found this video on youtube and it solved my problem

youtu.be/5Fl3GVsDXFQ