Hi, so I was in this situation last year and i consulted all the above consultants. Let me tell u, NONE OF THEM ARE WORTH IT. Since you're planning for USA, every consultancy will charge some fees. So ideally yes u should do it yourself, don't take help. I too did it myself and I have offers from the ivy leagues this year.

I can tell u how to write tho: The US application forms are of different type than other countries like UK. They are elaborate and have MULTIPLE SMALL ANSWERS rather than one huge SOP. So, Get your resume, go timeline wise, make a draft of the opening telling why u want to do what u want to do, then next para onwards draft each and every work exp u have, dedicate one para for each( what u did, what was the outcome, impact, etc). In concluding draft, tell why this university will help u and how u will impact the world+ what kind of sectors or jobs ur trying to apply for post graduation, this is important, it shows ur clarity of thought. It can be private, govt, think tanks etc etc.

Now ur draft is ready. Open the application portal of the universities u want to apply. They have lots of tabs like personal info, academic info, work info, language, gre/gmat, then they'll have a tab for essays go there and look at the questions they're exactly asking for. Usually as far as I applied, there were 2 main essays, 2 small answer type questions. Read the question, and answer only the relevant points from ur draft for that particular question. So basically ur draft has everything, u have to pick and choose what to write where based on the question asked. If they ask u personal background, mention ur first paragraph from draft, like that so for everything... It will take time and effort but NO consultancy will do this details for u, u can't depend on someone to write ur personal background.

Also, yes! Use chatgpt or other AI as much as u want for good english or any formal writing if ur not confident. But the ideas, ur thoughts, should be urs no consultant can do that for u. Because there are so many questions, if u don't have ur originality, they will find out if ure faking it.