Is there a forum (comprising of grad students, maybe even postdocs or PIs) which would help me review drafts of my SOP or the cold emails I wish to send to prospective PIs or my academic CV? I am applying for a PhD program in physics, if that's useful.
I think part of the goals in the PhD application process is to know what you want to learn, and how you want to contribute to that position. If you do not know that, then it is not a good fit for you. If you feel you need to learn the skill to draft such documents, then you can find plenty of websites on the internet where you can learn how to structure and write them. In many cases, your undergraduate/Master's professors and lecturers might be able to help you if you request them reasonably before time. Some PhD advertisements would also mention the page limits and the margin/font size for such documents.