To create selfies, we can simply use the front camera of the Samsung device, there is no second app or anything like that, just tap the "switch" to change the camera.

Android 11 | One UI 3.0
Step 1: Tap on  Camera
Step 2: Select  Photo/Video mode
Step 3: Tap the  Camera switch button
  1. Tap on Camera
  2. Select Photo/Video mode
  3. Tap the Camera switch button

Samsung Instructions