This is a take-off on the answer of Louic.
If you have confidence in your results then there is no need for this. Just submit to an appropriate journal and you will get the feedback you need.
But, for those cases in which you aren't sure...
This is why it is so important for newer researchers to form wide circles of contacts within their field. People who know enough, and are trusted enough, to give feedback on ideas and even read and comment on drafts and work in progress.
One way to do this, if you are at a large-ish institution is to form or join a research seminar devoted to a small set of topics. Papers can be passed around for comment. The coffee lounge is also a good place to do this, though it is probably something online these days.
Making contact with people at conferences (real or virtual) can help you build that circle. You can ask your advisors to be included in their circles. But, for effective research in the modern era, a circle is essential for most people, but especially for those at the start of their career.
But, cold emailing people isn't very likely to be effective. People don't know (or trust) you nor you, them.
And don't neglect to include your own students in your circle(s) as they develop.