To develop an ability, you need to practice the bits you don't do well as yet.

If you want to extend your vocal range, you need to practice the notes at the ends. But if you just force things, you may damage your voice. You need to consult someone who is trained in teaching people to extend their vocal range, i.e. a singing coach/teacher.

Otherwise, you just have to fake it - and you will get lots of advice here - a bigger bunch of fakers there isn't! ;-)