Ive been involved in photography since the late ‘70’s and taught photography for 4 years at MSU, worked for AP and International Herald Tribune.
My job was to come back with a photo, not worrying about my camera not working the way I want it to. If a third party app is the better tool for a specific job or photo, use it. I couldn’t care less what camera or app took it.
Yes, DoF is a zone of acceptable sharpness that extends both in front of and behind the point of focus (subject). If I misstated, it could have been a typo. Sorry for any confusion it may have caused.
Post your group shot with ISO, shutter speed and f/number and which lens or zoom setting.
You may also be interested in learning Apple iOS 18.2 public release is rolling out around the world in many (all?) countries today. I watched a video from someone in Australia an hour ago and he’d installed the update and reported that it resolved many of his issues. The article below explains how to update. The release time in your area may not have occurred yet. You will just need to check the update option in your iPhone.
Update iOS on iPhone