Improve the correct display and adaptability of the site on apple products?

Question

iOS

There is a site under development, which, when tested in the built-in browser tools, works fine at different resolutions, but when you view this site on a macbook or using the site https://www.browserstack.com/ - some elements are not displayed correctly, namely in this case, the header, which should be displayed at a screen width of up to 1000px, is displayed on a macbook up to 1300px of the screen width.
I connected different normalizes, there was no effect. What could be the reason?
While writing, I thought about the retina, could it be the reason for this behavior?