Biological sex is fixed at conception, can be discerned in utero, and is immutable.
There are relatively new studies underway to determine the effect of hormones on transwomen over time *however* there is nothing to date - I repeat nothing - to indicate that any reduction in say, muscle strength, would make the biological male 'equivalent' to a biological female. In any case, males have other significant physiological advantages such as longer limbs, greater lung capacity, different skeletal build (look up 'Q angle' and running if you don't know what that means), none of which are affected by hormones.
A couple of examples:
In the USA, a young transwomen, who was a mediocre male athlete, is now winning state championships, running against females.
https://www.letsrun.com/news/2019/0...an-for-3-years-just-won-an-ncaa-womens-title/
In the recent Pacific games, a 41 year old transwoman won weightlifting gold, competing against females half their age.
https://www.theguardian.com/sport/blog/2019/jul/22/current-impasse-transgender-athletes
Some more info for anyone interested:
https://fairplayforwomen.com/emma_hilton/ (video & transcript of a recent presentation)