Hello anjali133,
Thanks for using Apple Support Communities. It's our understanding that your iPhone 11 Pro display intermittently has a green tint. You've come to the right place! We're here to help.
First, make sure that your iPhone has the latest software version.
Update your iPhone, iPad, or iPod touch
If the issue persists, restart your iPhone. Restarting can resolve many behaviors
Restart your iPhone
Also, confirm that you don't have any Color Filters applied from the Accessibility menu. You can check this by going to Settings > Accessibility > Display & Text Size > Color Filters.
Use display and text size preferences on your iPhone, iPad, and iPod touch
Let us know the results. Does this issue occur if you choose a different wallpaper? Please include any other troubleshooting steps that you may have tried.
Have a nice day!