With Samsung's One UI user interface, the lock screen can be personalized to change the clock displayed, and in addition to different clock styles such as digital or analog, with/without seconds or date, even the color can be customized.

Note: Is Roaming Clock activated, the Clock cannot be personalized on the lock screen.

Android 10 (One UI 2.0)
Step 1:  Open the  Settings
Step 2:  Tap on  Lock screen
Step 3:  Tap on  Clock style
Step 4:  Tap on  Lock screen
Step 5:  Choose desired  Type
Step 6:  Tap on  Colour
Step 7:  Choose desired  Colour
Step 8:  Confirm with  Done
  1. Open the Settings
  2. Tap on Lock screen
  3. Tap on Clock style
  4. Tap on Lock screen
  5. Choose desired Type
  6. Tap on Colour
  7. Choose desired Colour
  8. Confirm with Done

Samsung Instructions