FYI, generally, Smooth Motion is useful if you have low FPS in games that don’t support DLSS and/or Frame Generation. Since MSFS already has those, it’s up to you whether you prefer to use Smooth Motion or stick with DLSS and Frame Generation in MSFS settings.
If you’d like to share your thoughts about Smooth Motion, feel free to join the discussion in the thread linked below.
https://forums.flightsimulator.com/t/smooth-motion-for-rtx-40xx-50xx-worth-it-for-msfs-testing-and-impressions/734426/