Is it possible to resize document.documentElement.clientWidth somehow?

Question

PHP

Good afternoon!
Is it possible to change the size of document.documentElement.clientWidth somehow ?
When I visit the site, document.documentElement.clientWidth becomes 1200, no matter what phone I come from
. And if I turn on the PC version or go from a PC, then the screen size is set based on the screen size, even if the viewport meta tag is set

Answer 1

Where is the code?
If you "compare" something like this
if(document.documentElement.clientWidth = 1200)
then it will be 1200 everywhere xD
And without details in the form of code, this is crazy nonsense.