Converting Profile PS CC 2020

Actually that second link is incorrect. An untagged file is not represented in Monitor RGB, as it will be in an application that lacks color management altogether. It is represented in your working RGB. There's a difference.

The color management engine in Photoshop cannot be turned off. It always runs, and the whole application architecture revolves around it. There has to be a source profile - and if there isn't one embedded in the file, the working RGB kicks in.

The only way to truly disable color management in Photoshop, is to make sure source and destination profiles are the same. It doesn't matter which one, as long as they're the same. Then the conversion will always produce a null result - nothing happens - which is the definition of no color management.

Whether you assign the monitor profile to the document, or vice versa, is immaterial. The result is the same: the RGB numbers are passed directly to screen, uncorrected. This is also what an application without color management does.

Hi, color managment is a complex thing, please take a look here:

https://helpx.adobe.com/photoshop/using/understanding-color-management.html

And here:

http://www.earthboundlight.com/phototips/untagged-rgb.html

However if your monitor is calbrated and profiled, you can try to assign different profile to the untagged image, and choose the profile that rendered the image in a pleasing way.

An untagged file is represented in your working RGB. That's the source.

A profile conversion is actually impossible with an untagged file - there is nothing to convert from. So a source profile is assumed.

Color management happens all the time in Photoshop, not only when you convert. Everything you see on screen is converted from the document profile into your monitor profile. Same principle. An untagged file is displayed according to whatever your working RGB is.