Photoshop doesn't run default sRGB for anything. Depending on settings it either respects the color profiles of files, ignores or assigns/converts to one. The default installation settings for Photoshop CC has been "respect when available, ignore/don't assign when not".
In terms of view transform, Photoshop reads the color profile of system (Windows, MacOS,etc..). So Photoshop always shows the correct color (if the color profile aligns with the monitor gamut).
I wrote probably 20 essays on this topic on this forum, but currently 3dsMax, and Corona, still ignore system color profile (which is mostly ICC).
4) If I use "assign profile: Benq PD3200U" AND check "and then convert document to working RGB", what I see is the same as the VFB and I'm working with a standard profile.
This is of course perfectly valid from creative standpoint, but it's wrong from color management. It only gives you identical colors between VFB and Photoshop because you essentially translated your RGB values into incorrect ones to match the incorrect result on VFB. And because both are now incorrect, they both look the same. Not sure if that is positive :- ). But I know a lot of people with wide gamut do this, it's pretty popular "hack".
To have
identical and correct colors between 3dsMax/Corona VFB and Photoshop, you need to physically clamp color space (space, not profile describing one) of the Display down to sRGB. That needs to be done on hardware level, in monitor OSD menu either through factory calibrated profile (the Monitor stores 14bit 3D LUT, not ICC profile) or custom hardware calibrated profile (again, stored as 14bit 3D LUT internally in Monitor OSD, not in Windows).
BenQ PD3200U doesn't offer hardware calibration, so you are stuck with factory profile which is ok because it's pretty good.
This is correct workflow for this monitor for 3dsMax/Corona.
1) Monitor OSD Menu: Select sRGB mode. Then adjust brightness to your liking. (Fun fact: Calibration is also done to exact brightness levels, but if you move it +/- 50perc. the difference in accuracy is not drastic).
2) Type Color management into taskbar in Windows, select your monitor, check "Use my settings" and select "sRGB" ICC profile. Set "Use as default".
3) When loading any rendering into Photoshop, you don't need to do anything if your settings are set to "Don't Ask". It will stay unmanaged and you only need to "Assign" sRGB profile at the end of export, for examply when saving to final file. Don't convert to any other profile.
The above workflow doesn't work for high-gamut displaying (DCI-P3, HDR workflow,etc..) or printing (AdobeRGB, LAB,etc.). But since 3dsMax & Corona are not color managed (Autodesk Maya and Vray for example are), this is the best scenario to use right now. Least headaches. Colors are always correct, you're just not using wide-gamut capability, which is ok since most devices are sRGB only, even today.