What is the best way to improve website promotion using the mobile version?

Question

Marketing

Good afternoon. I ask more experienced programmers to suggest

There is site.ru with adaptive design (Verification systems confirm that it is optimized for mobile devices, so that's all right). And the question is: will promotion improve if a separate mobile version of m.site.ru is added ? (At the same time, while maintaining adaptability both on site.ru and on m.site.ru - just in case)

I somehow noticed that sites with the m. are given higher in the search, and if it was not an accident, then, as I understand it, it is only necessary to add the following (On site.ru) to avoid duplicates?

<link rel="alternate" media="only screen and (max-width: 640px)" href="https://m.site.ru/<?php echo $url;?>" />

Answer 1

The test showed that it will not improve