Hello!
Himself recently asked this question. You can, of course, do everything yourself – upload to streaming platforms, monitor everything. The same applies to post processing – mastering and mixing. But this is a huge waste of time.
There are a bunch of sites where all this can be done quickly and relatively inexpensively. I tried several services and so far I have stopped at theamadei.com. There are pros and cons, as elsewhere, but so far everything suits me.
Test different services, choose what is most convenient for you and use.
I wish you creative success 🙂