I can’t find 0.5 at my iphone 11 pro max camera

Hello Atiehtq and welcome to Apple Support Communities.

I see you are not able to access the .5 zoom setting on your iPhone 11 Pro max when in Photo mode.

Are you running the most current version of iOS (13.2.3 at the time of this post)?

As this is presenting as a software issue (or you would not see the option when in Video mode) and the Camera app is not able to be deleted and re-downloaded, if you're already running the most up-to-date version of iOS, you may need to consider reinstalling iOS on your device. While this shouldn’t affect any data stored on the iPhone, it would be a good idea to make sure you’ve got a backup in place: How to back up your iPhone, iPad, and iPod touch - Apple Support

Once you’ve successfully backed up your device, follow these steps to reinstall iOS, making sure to choose “Update” when prompted: If you can't update or restore your iPhone, iPad, or iPod touch - Apple Support

Cheers.