The best habit to restore deleted photos and videos from Samsung Galaxy S9 is to look to recover from Backup.
If you have been using Samsung Smart Switch to backup data, then restore from there.
If you have been using Google Drive to upload photos and videos, then restore from Google Drive.
Look in to the Google Photos app trash bin, if you are using it.
Look in the Recycle Bin/Trash/Recently Deleted folder in the Gallery App. The deleted files remains there for 30 days.
If you do not have backup, even then you can try any third-party tool to recover deleted photos and videos from Samsung Galaxy phones.
Follow the solutions mentioned here - https://joyofsmartphone.com/deleted-video-recovery-from-samsung-galaxy/
Maybe this can help you!