Ring lights are great, but you don't always have one at hand. Almost everyone has a phone, and a phone at full brightness showing a white screen is a passable softbox in a pinch.
For selfies, hold the phone slightly above and to the side of the camera — this gives flattering downward light. For product photos, place it behind or beside the object to fill shadows.
Use BlankPane to show pure white (#FFFFFF) at full brightness, then adjust your phone's brightness up. Dim the screen to create a warmer, softer fill when needed.
Bonus: a white screen works as an improvised light panel for video calls, small interviews, and stop-motion shots where you need even, shadowless light.