One of you needs to be physically living in Canada to sponsor your child for PR - and that person must remain in Canada while the child's application is being processed.
If both of you are outside of Canada, you should apply for a TRV to bring your child to Canada with you before applying for PR. If the TRV is refused, then you can try applying for a TRP. If the TRP is also refused, then one of you will need to travel to Canada ahead of the rest of the family to sponsor the child for PR. The other parent and the child will be able to travel to Canada after about 6-8 months once the child's PR visa is approved.
Make sure you meet the PR residency requirement when you apply to sponsor the child.