There's a limited amount of data out there, but what there is tends to show consistent deterioration in athletic performance. This systematic review published in 2017 (
https://link.springer.com/article/10.1007/s40279-016-0621-y), for example, concluded that "there is no direct or consistent research suggesting transgender female individuals (or male individuals) have an athletic advantage at any stage of their transition (e.g. cross-sex hormones, gender-confirming surgery)."