Some useful background info … Not an answer.

HDR10+ …https://en.wikipedia.org/wiki/HDR10%2B

PCMag …https://uk.pcmag.com/tvs-home-theater/71182/what-is-hdr-high-dynamic-range

https://www.cnet.com/tech/home-entertainment/what-is-hdr-for-tvs-and-how-does-it-make-the-picture-better/

You can enable VEGAS Pro HDR or ACES color space and assign IDT Color Space Profile REC2020/REC2100 to properly conform to REC709

Tho, you still need to manually tweak the exposure using the Color Curve and bring back some saturation.

Only Resolve Mac OS version seems able to do the conversion properly (Not even the win version)

@alifftudm95 sorry, did not understand anything, not much of a techie here. I tried what you showed me in the screenshot, but it hardly helped.

@Furqan You need to ask exactly what you don't understand.

You can use ACES color management by setting the project properties to 32-bit full. View transform to sRGB assuming a normal non-HDR display. Then when you assign that color profile the colors will change.

After that use the color grading panel to adjust saturation and contrast to taste.

Don't know much about this. Tried a test sample from Samsung S24 which uses HDR.

#1.So, in Project Properties toggle "HDR Mode" to HLG since according to Roger HDR is not supported.

#2. Once that's done right click media file in "Project media" pane and select "color space".

This gives a list of various cameras colour spaces but Samsung/iPhone is not one of them.

@Furqan Maybe make a sample iPhone clip available via dropbox or equivalent and users can select best match to it. in #2. above.

With rec 2020 1000 nits selected I than applied a levels FX and adjusted the Gamma to match what looked right/similar to VLC output. Media player Classic doesn't output as good as VLC. This is of course a complete kludge workaround, given no HDR and no Samsung HDR10 support, but output looks fine.

To render out you need to remove render filter which is automatically applied as HDR. Then select non HDR render.

Johnny, you wouldn't turn on HDR mode (HLG or HDR10) if you don't have an HDR monitor as you can't accurately see what you're doing.

Alex suggested just a generic REC2020 color profile as there isn't a phone specific one.

I meant to say that I don't have any HDR monitor, other than a modern Samsung 4K TV.

So, for Samsung S24 phone. Maybe something similar can be used for OP's iPhone.

With Project Properties "HDR mode" set to OFF
With Media properties Color space set to Rec. 2020 ST2084 (1000 nits)
With "Mark-Y" luts used as in this thread ...

https://www.vegascreativesoftware.info/us/forum/problem-with-samsung-s24-ultra-vdeos-and-vegas-pro--146583/

Version 1 -- Conservative levels, good in studios.
Version 2 -- Liberal levels, outdoors and even lighting.
Version 3 -- Very conservative. Animations, colored LED lighting, special effects.

Mark-Y's Download link ...

https://www.vegascreativesoftware.info/us/proxy/9118d40836d176d5c140/?link=https%3A//drive.google.com/file/d/19Hx_Kv6ThYYEBSjOfWO-M-0JvfVPxa-0/view%3Fusp%3Dsharing

Of course highlight detail is lost.

Transform LUT or ACES is either / or.

Either use view transform (sRGB for standard monitors or another one for HDR ones) and the color space or alternatively view transform off with the LUT.

Make sure the color range matches the footage (full or limited) if VEGAS isn't reading it correctly (22 metadata reading is mostly fixed as far as I could test).