Hi there Christace,
From what we can tell, you're not seeing the Ultra Wide (0.5x) lens option when taking photos using the Camera app on your iPhone 12 Pro. We'd like to learn more to see how we can help.
If you go to Settings > Camera, is the 'View Outside the Frame' option turned on? If not, let's turn it on and test from there. Learn more from the 'Turn view content outside the frame off and on' section of this link:
Use Camera settings on iPhone
Zoom in or out
- On all models, open Camera and pinch the screen to zoom in or out.
- On iPhone models with Dual and Triple camera systems, toggle between 1x, 2x, 2.5x, and .5x to quickly zoom in or out (depending on your model). For a more precise zoom, touch and hold the zoom controls, then drag the slider right or left.
Keeping that in mind, let's be sure you're following the correct steps to zoom in or out from the 'Zoom in or out' section here:
Take photos with your iPhone camera
Thanks!