First let's clarify the components here.
Sexual desire/need isn't really testosterone specific. Most people still retain their sexual desire on HRT, though often reduced. It takes a while, though. But typically, you won't lose sexual desire with HRT alone, it's just a little different.
Erections are different, but similar. Women also have erectile tissue, and it's similar how it's activated, but they don't generally maintain the "erection" throughout the entire sexual encounter. Most mtf people experience a lot of difficulty in achieving and/or maintaining an erection after a year or two on HRT, timing is different for everyone, but it takes a while.
Many mtf people get an orchiectomy to reduce these things and reduce the need for the androgen blockers.
Anecdotally, I had vaginoplasty after about a year and a half on HRT. I didn't take androgen blockers during my initial HRT, just Estradiol, so I can't really say how they affect things. But towards the end, I was losing the ability to maintain erections for more than a few minutes at a time, and ejaculate was often very minimal. Also, the orgasms themselves became less of a spike and lasted longer. After vaginoplasty, I still have the need to masturbate, but it's definitely not as intense, and I dont have as much anger and frustration build up if I don't masturbate for a few days. Masturbating takes way longer, though, but orgasms are still something I enjoy and helps me relax.
I know some mtf people who do not choose or dont have the means to get vaginoplasty will have an orchiectomy to help make these changes happen as well as eliminate the need for androgen blockers and their side effects.
If you truly want no ability or desire to have sex, it's mostly irreversible, but you can get "nullification" surgery. Basically all external genitals are removed and only a hole for the urethra is left behind. This surgery can leave some penile nerves intact or totally remove them so there's no ability to orgasm. But the psychological need for orgasms still takes time to fade from what I've heard. But it will be less than with just HRT. Not something most doctors will recommend, but it is sometimes done for asexual people.
