there isn't any alternative (and simpler method)?
anyway Thanks for the answer
No. Because, re-scaling isn't something straightforward.
The only logical way to do that is to change the viewport and re-adjust the game accordingly.
Even if there was a re-scale button on the Construct 3 editor, it would just destroy the game.
Also, it's hard to pinpoint which to scale.
Coordinates, parallax, layers, images, collision polygon and sizes would adjust to a weird size.
Hence, breaking the game.
It would be unpredictable to do it that way, changing the viewport size and adjusting manually for the new viewport size is the logical way to achieve this.
There is a tutorial on how to make a one screen design to adapt to other screen resolutions and aspect ratios. That's an example on how developers usually achieve multi-screen support.
Link : construct.net/en/tutorials/supporting-multiple-screen-sizes-17
Although, this is for the runtime. And you need to have pre-made your game to support multiple device screen sizes in the first place. Like for Scale Outer and Scale Inner, which are common for mobile, uses the anchor behavior or events to scale to different screen sizes.
I hope that shed some light on the subject.
No problem. You're welcome.