Hi tahm77
Thank you for your question, and photo
Re: What I want to know is, can this work the way I want it to?
Experimentation is wonderful! Yet there is also the need to get know what the software can do best, and what it is set up to do, so we can take advantage of both aspects. Is portrait mode the best place to experiment with nature photography ... maybe so, maybe not.
Seems "Portrait mode" can only work the way Apple has set it up to work.
Software rarely bends to the wishes of users, except for allowable customisations etc.
Seems to me that "Portrait mode" is mainly designed to take Portraits, ie faces,
where there is mainly one large shape and a less important background.
Apple support has various articles online, for us to get familiar with what the mode has been set up to do expertly.
Use Portrait mode on your iPhone - Apple Support
Eg: says:
"Some iPhone models have multiple options for Portrait mode, like 1x or 2x. Just tap the 1x or 2x button to switch between the options. With iPhone XR and iPhone SE (2nd generation), the rear-facing camera must detect a person's face to take a Portrait mode photo"
Take Portrait mode photos with your iPhone camera – Apple Support
says
" you can apply a depth-of-field effect that keeps your subject—people, pets, objects, and more—sharp while creating a beautifully blurred foreground and background"
Your fine example demonstrated how the the blurred foreground appears with multiple objects in the frame.
Edit Portrait mode photos on iPhone – Apple Support
says:
"Note: To remove the Portrait effect from a photo, tap Portrait at the top of the screen."
You might want to check that out on your example photo. eg: Does it fix the "disaster"
Also:
"Use the Depth Control slider (on supported models) to adjust the level of background blur in your Portrait mode photos".
Might be fun to experiment further with what you can do after taking a photo!
Change the lighting of a Portrait mode photo in Photos on Mac – Apple Support.
says:
If a Portrait mode photo offers a Light option, drag the Light slider to adjust the appearance of light in the portrait.
So experimenting seems the way to go, before finding a satisfying answer to your question.
I don't think anyone can give you a yes or a no, really. It all depends ...
Sometimes those with the expertise make it easier for us by sharing their knowledge online.
All the best :-)