Most schools provide decisions that are consistent with your FA needs. So if they can’t offer you FA and you have requested it, you will be rejected. Whether their assessment of your need matches theirs is a different matter.
Sometimes, you will be waitlisted and told you will be admitted if FA becomes available. This would be the result of students who were admitted with FA not accepting those places, and basically replenishing the FA funds.
There are a couple of schools who will provide an acceptance but no FA, knowing you need it, but these are rarer.
If you can afford to pay, they expect you to do so. I think sending a letter will help you get admitted and will likely also result in you having to pay.
Also, if you plan to attend university in the US, you will need funding for that too, and again as an international student, you will be in a tough pool. Having done a PG year in the states won’t change that, and having high FA need may make it difficult for you to be admitted to a u.s university. That will be a challenge for BS too unless you can demonstrate that you can return home for college.
If you are such a strong applicant that there is little question about a college placement, it may behoove you to just apply to college although you have said in another thread that you don’t want to do that.