For those interested in this, Leica LUX is the alternative iOS Camera. It also works for those who cannot afford to own a Leica.
https://leica-camera.com/en-SG/photography/leica-apps/leica-...
https://leica-camera.com/en-SG/photography/leica-apps/leica-...
When using a DSLR I almost always shoot in (A)perture mode, it helps you control how much you separate the subject from the background and it's the thing I miss the most on phone. The portrait mode isn't quite the same.
It's the first app that I came across to have an aperture mode, cool.
PS: Apparently it lets you capture in all modes, but to edit the parameters after taking the picture it requires the pro mode.
Basically you want to make sure probably to use real focal lengths (disable digital zoom). This applies to all iPhones and androids.
Usually the main (normal) focal length camera will have the largest sensor and best aperture. Have the phone focus on something close and find the closest distance the phone can manage. This will create the biggest background blur.
On phones with longer length telephoto this will often also work if you find the closest focus point and do the same process. Depending on the actual focal length to sensor size ratio (and aperture) of the telephoto lens it may either have more or less blur than the main camera.
The Ultrawide will usually never have much background blur ability but that is generally true for a real DSLR as well
I recently used the B/W preset by Greg Williams during my trip to Iceland, and the results were fantastic. The grainy texture it added to my photos was exactly what I was looking for and really enhanced the dramatic Icelandic landscapes.
But I hate subscription apps. And the rest of the UI seems quite clumsy.
Lightroom mobile also actually might require a subscription to edit raw files however (then again it can do a lot more for the price). It also has a free version and you might have good results shooting in a high quality .heif