Samsung offers its users of smartphones and tablets with One UI a high degree of personalization options, including a different theme, where not only the icons are exchanged, but also the background (but can still be changed as usual) and sometimes the style of standard apps. Some themes that can be downloaded for free/paid via the Galaxy Store also have animated lock screens.

Android 10 (One UI 2.0)
Step 1:  Open the  Settings
Step 2:  Tap on  Themes
Step 3:  Tap on  My Stuff
Step 4:  Choose  Theme  you want
Step 5:  Confirm with  Apply
  1. Open the Settings
  2. Tap on Themes
  3. Tap on My Stuff
  4. Choose Theme you want
  5. Confirm with Apply

Samsung Instructions