1.Go to 
Settings > 
Always-on display & Lock screen > Lock screen clock format.
2.Choose a Lock screen clock layout.
Note
You cannot change the format when Dual clock is on.
You cannot change the Lock screen layout for the third party themes.
Settings > Always-on display & Lock screen > Lock screen clock format.2.Choose a Lock screen clock layout.
Note
You cannot change the format when Dual clock is on.
You cannot change the Lock screen layout for the third party themes.