There is no special app for the flashlight (torch) on the Samsung device. The flashlight can be found under the status bar as a quick setting where it can be switched on and off.

Android 10 (One UI 2.0)
Step 1:  Open the  Notification bar
Step 2:  Open the  Quick settings
Step 3:  Turn on/off  Torch
  1. Open the Notification bar
  2. Open the Quick settings
  3. Turn on/off Torch