First Generation PRs under GIP (Global Investor Scheme) or Professionals/Technical Personnel and PTS (Skilled Workers Scheme) are exempted from the NS. However, the Enlistment Act requires the male children (2nd Generation PR) who are sponsored by their parents in the PR application need to serve the National Service.
Some people file PR application only for themselves and avoid it for their male children. However, this can have a negative impact on your PR application.