How to get (a payed?) feedback with discussion?
It is extremely country specific and strongly cultural.
I can explain how I would do in your shoes in France. You need to adapt my hints to your country.
I would first attend several university PhD level seminars (or at research institutions like CNRS, CEA - I am employed at CEA, LIST but soon retiring - , INRIA, INSERM or Grandes Écoles like Polytechnique or ENS Ulm or ENS Paris Saclay -from which I graduated-). Or even Collège de France ones. BTW, Grandes Écoles and Collège de France are very French, you are unlikely to find equivalents in other countries.
At seminars with a small audience of less than 30 persons, you are allowed (at least in France) to attend them freely (no need to pay) and to ask clever (and politely) questions. You'll use Google or the Web to find such seminars.
Any scientific researcher is very happy to get oral feedback, as long as you respect his work (even if your opinions are different). That is part of the science game since at least Newton.
Then you have established some direct contact. Discuss with them your ideas. They might be interested. If they are, send them by email your draft and ask for feedback.
BTW, you should attend peer-reviewed conferences in your field of expertise. If in Europe, consider being part of some H2020 or HorizonEurope submission. Being inside a putative consortium submitting some research grant proposals will teach you many related skills. But you need to accept and contribute to your part (or even a bit more) of the submission efforts, and research grant submissions are generally highly selective (less than 10% of proposals get funded).
Read hundreds of scientific papers (in journals or peer-reviewed conferences) related to your field and scientific interests. Be sure to have a good bibliography of citations in your own text. A priori, several dozens of references (e.g. using BibTeX for your LaTeX paper).
At last, if you can afford that, consider starting some PhD. Your advisor will teach you most of these soft skills, including scientific writing skills, because that is part of his/her job.
My answer to another question on this forum also contain some useful hints.
PS. A poorly known fact is that on the average, every scientific publication has less than 2 or 3 readers. As Higgs explained in his Nobel prize talk, the "publish or perish" mindset of current academia is globally counter-productive: most of the research papers I am reading these years give a sense of déjà vu.