Testosterone is converted to DHT by 5a reductase. DHT has several times the affinity for the androgen receptor that normal testosterone does and is very important in the cause of body hair and male pattern baldness.
You can target testosterone and DHT in more or less three ways that I know of:
Stop only DHT with 5a reductase inhibitors (a type of antiandrogen) such as: dutasteride, finasteride, etc.
Increase estrogen levels (as E and T act in opposition to eachother increasing E will suppress T, although it should be noted that T is usually more effective at suppressing E than vice versa - which is why MTFs generally need anti androgens and E, while FTMs only need T)
Antiandrogens (like 5a reductase inhibitors but block both DHT and T, sometimes in roundabout ways) will decrease the levels of DHT and T as well (or at least the effective levels, some Non Steroidal Anti Androgens tend to raise serum T but lower available androgen receptors for binding), these include : spironolactone, cyproterone acetate, bicalutamide, enzalutamide, nilutamide, flutamide etc.
Any of these will work to reduce hair loss. I would however suggest doing either 1 or 3 depending on what you want to happen with your body as number 2 is not only dangerous on your liver and risks massive amounts of clotting but will also throw your emotions all off kilter.
If you want to transition I would suggest 3 as they are more useful that option 1
If you just want to get rid of androgenic alopecia I would suggest using option 1
