G: To stop your iPhone 12 from dimming the screen automatically, you'll want to disable Auto-Brightness and possibly True Tone and Night Shift if they’re affecting visibility. Here's how:

1. Turn off Auto-Brightness

Apple hides this setting in Accessibility:

• Go to Settings > Accessibility > Display & Text Size
• Scroll to the bottom and toggle Auto-Brightness off

2. Turn off True Tone

This feature adjusts the screen based on ambient light, which can make it harder to see in sunlight:

• Go to Settings > Display & Brightness
• Toggle True Tone off

3. Turn off Night Shift (optional)

It can make the screen look dimmer or warmer:

• Go to Settings > Display & Brightness > Night Shift
• Set Schedule to Off, and Manually Enable Until Tomorrow to off

4. Disable Low Power Mode (if enabled)

This can also dim your screen:

• Go to Settings > Battery
• Toggle Low Power Mode off

5. Keep in mind: Thermal dimming

If your phone gets too hot (common outdoors in sunlight), iOS will dim the screen anyway to prevent overheating. There’s no official way to disable this. Best workaround: shade the phone, reduce background app activity, or use a cooling case.

Let me know if it’s still dimming despite all that—there may be a specific combo at play.