Yes, there is a split, and so with docs about to prescribe it.
One way to look at it, is doing your blood test, find out where your P is. If low, it be a good idea to take some, or?
Next, as it happens, E can get jolly high (E dominant) and then taking P is a good idea, because it opposes E. As it happens in the normal ups and downs of the natal female cycle.
Beyond all of this, in comes the idea it would 'help' with breast growth, i.e. make your boobies some what fuller, plus some other more vaguely defined pros, i.e. general well-being.
That being the idea alone, it is not usually sensible to prescribe it before 1 year+ into HRT. YMMV
Lastly, P, by opposing E, tends to check water-retention AND, E going 'wild' on cell growth, such as causing endometriosis in natal females (not 'our' issue) but ALSO to check E on things like breast cancer. Not normally an issue for 1 year+ on HRT. YMMV
It also makes for more appetite, yet reducing water retention (see above) AND can make you more relaxed --- to the point of getting sleepy when taken.
It is available in oral or cream form, the injectable non-micronized version of P (medroxyprogesterone acetate) is loads more powerful and a lot more prone to cause depression.
Oral (tabs) also tend to load your liver some more, one reason to consider not to just take it for the hell of it.
I hope, I have not left out any major item other then that Depo-Provera (medroxyprogesterone acetate (DMPA) can play havoc with your mental health, as Zoë.
Axelle