This is the most important step for most people who are transitioning, but it is also the most complicated. Most uninformed people just think they need to change their pitch and poof magically they will be thought of as a girl when they speak. But first that is difficult to achieve, and second even with a complete pitch change your methods of speaking will out you just as much as the pitch will.
Male voices typically have a different rhythm, a different tone, different emphasis on high and lows when speaking, and even tend to use different word and sentence structure choices.
All of that being said though, I can probably help you out with at least changing your pitch.
First I have a binaural beats file for you. In general these entries on yt fail miserably to do what the authors claim of making feminization changes, because they have not actually applied actual science to the problem. However this one actually correctly hits a certain pitch which does nothing to change your brain, but prolonged exposure will cause you to subconsciously change your pitch.
https://www.youtube.com/watch?v=lyteLDyhjEs
Next I have a link for you to test your pitch to see if it is in the "female thresholds".
https://primaryobjects.shinyapps.io/voice/
Third I have another yt video link for you which is a shortcut for getting your voice to match a "female pitch" using a smart phone app. Personally have not tested this, but the logic seems sound - pun not intended.
https://www.youtube.com/watch?v=Wq43BGNeAzQ
Next I have a few videos that you should probably check out on yt that deal with voice changing practice…
https://www.youtube.com/watch?v=hWHGS7s7ffY
https://www.youtube.com/watch?v=q6eTvS2wIUc
https://www.youtube.com/watch?v=LnYrWfAGj_c
https://www.youtube.com/watch?v=9xu_vFkKq4g
https://www.youtube.com/watch?v=Ch5gBKsvSwo
https://www.youtube.com/watch?v=pY1wrXN-vSg
https://www.youtube.com/watch?v=5Rw4G5joEWw
That is before we get into actual hypnosis files… if you need hypnosis respond back and I'll see if I can get you a comprehensive list of possible files.