An alternative to Dev Tools for responsive layout?

Question

css

Good afternoon!
Based on my meager experience, and the comments of the Specialists, I assume that "glitches" in Dev Tools, when viewing a page at resolutions other than yours (320 * 568; 1920 * 1020, etc.) are a rather frequent and widespread phenomenon. You can spend a day looking for - non-existent - errors in markup and css.
Question: Tell me please, what do you use for viewing with adaptive layout?
For viewing (at native resolution 1280*1024), how will the page be displayed on a 1920*1080 screen?
If we talk about extensions (an example of Resizer), then in my opinion they do not correctly display how the page will look on a monitor with a resolution of 1920 * 1080, on your native monitor 1280 * 1024 ...?
And how, when working in Dev Tools, to understand that this is currently a "glitch" and not a bug in the code?
Thank you!

Answer 1

firefox - "responsive design mode" - enter any size (Ctrl + Shift + M)
in chrome you can also

Answer 2

in general it would be nice to have two monitors and usually zooming in / out of the window works fine.