Hi there 1christianGal,
We understand you'd like to adjust the focus for the camera on your iPhone 13 Pro.
Check out how to do so with the section below from Use iPhone camera tools to set up your shot:
"Adjust the camera’s focus and exposure
Before you take a photo, the iPhone camera automatically sets the focus and exposure, and face detection balances the exposure across many faces. If you want to manually adjust the focus and exposure, do the following:
- Tap the screen to show the automatic focus area and exposure setting.
- Tap where you want to move the focus area.
- Next to the focus area, drag  up or down to adjust the exposure.
- To lock your manual focus and exposure settings for upcoming shots, touch and hold the focus area until you see AE/AF Lock; tap the screen to unlock settings.
On iPhone 11 and later, you can precisely set and lock the exposure for upcoming shots. Tap , tap , then move the slider to adjust the exposure. The exposure locks until the next time you open Camera. To save the exposure control so it’s not reset when you open Camera, go to Settings  > Camera > Preserve Settings, then turn on Exposure Adjustment."
We hope this helps.