Janie, I looked briefly at the threads. These two may be of some interest.
67949: Discussion
58021: Pitch

There are also threads about 'stretching' one's vocal range, but this is best done with professional guidance.

Most people are assigned a 'range' by a school or church singing group leader and accept that. With experience, the singer may develop a broader range.
Professional soloists, with voice training, may considerably extend their range. It must sound 'natural' or the audience will cringe and whisper.