Yes right before and during your period your cervix will drop slightly and be lower until your period is over with.
Then your cervix usually goes back up to where it was normally before.
Also just before ovulation the cervix will be slightly open as well and have a tiny opening about the size of a slit.
After ovulation and your period the cervix should close back up and then reopen again for your period.
After the ovulation occurs your cervix will become more firm and drop lower and your opening to your uterus will become tightly closed.
It can happen immediately or take several hours or even days to occur.