It can be possible for the FTM to lower their voice some without damage to the voice. We MTF start out with the chest voice where the muscles above our larynx are relaxed when we speak. To shift our voice to the feminine range, we tighten up those muscles and it gives us a sizable pitch increase. We call this our trained voice but in music it's a head voice. In addition when we speak, we feel the vibrations in our mouth. Women naturally use what we call a trained voice and if they relax the same muscles, they drop into the lower feminine range or sometimes into the upper masculine range. Karen Carpenter is a singer who made her money by dropping into the chest voice for her primary voice when singing. Her records were one of the first to use overdubbing so she was also her own background singer and you will hear her higher range in some of the background singing. A good example of this is her song "Only yesterday".
In addition, male voices are much less expressive. The human ear listens for things that say feminine in a voice and if it hears them, it ID's the voice as feminine. Staying in the lower end of the range will help keep the ear from triggering on feminine and may class your voice as young male.