This is probably going to be a disappointing answer (and way too long), but…from a technical point of view, it looks like nothing is wrong here.
What you want is understandable: You want to see the pixels in the image. Traditionally and obviously, this was done by using the “100%” magnification. Here is the problem: Practically all photo applications have defined “100%” to mean one image pixel to one display pixel (and not anything related to real world size). This worked great for all those years on older displays, where the ppi resolution was so low that you can see individual display pixels at 100%. Conveniently, we all got into the habit of using 100% for detail checking.
But that habit broke down as display resolutions started to increase toward print resolutions. The higher the display ppi, the less visible the individual pixels are. Older displays are in the range of 90–110 ppi. Newer Retina (Mac) and HiDPI (Windows) displays are 150 ppi and up. In that higher range, pixels get hard to see at 100% (1:1) magnification.
But photo applications (Adobe and non-Adobe) still define 100% magnification as 1 image pixel to 1 screen pixel. Technically, this means nothing is wrong: The meaning of 100% magnification has not changed. But practically, if we continue to think 100% means “I can see the pixels,” we are frustrated because we cannot see the pixels due to the higher ppi of today’s displays.
To boil it down, the root cause of the problem is that many of us got used to 100% as some kind of “actual size” when it never meant that, unless output was to the screen. 100% definitely never meant “actual size” if you wanted to print at something like 300 ppi. So one part of the solution is to recognize that 100% is not and never has meant “actual size.” unless you were a web designer. (And today even that doesn’t hold up, which is another long story.)
What’s the solution then? If you want to see image pixels, use a higher magnification, such as 200%.
Note that this is completely consistent with photography in general. What was “actual size” in the darkroom? The size of the print. Can you see the individual grains at print size/actual size? Not unless it is a very large print, otherwise you must increase the magnification, by using a loupe. Same here…you want to see the pixels, you increase the magnification.
Also, this will not be addressed by changing the display resolution in the macOS Displays preference. That’s because all of the Scaled resolutions affect only the UI resolution, not the content resolution. But all of those options always use the full resolution — every pixel — of the display. Changing the Scaled option to 3000 x 1692 pixels draws UI elements and text slightly larger than the display’s native 3840 x 2160 pixels, but they are still rendered using every pixel of the 3840 x 2160 display for full detail. The content itself, the photo, is also rendered using every pixel of the display; so when displaying 1 image pixel to 1 display pixel (1:1 0r 100% magnification) the image must be smaller than on an older, lower resolution display. Again, this is true in nearly all photo applications. The way display settings scale the UI separately from image content on Retina/HiDPI displays is consistent throughout macOS and I think Windows too, because it allows UI scaling while still using every pixel of the display.
How much smaller? A 27-inch 4K display is about 163 ppi. An older 27-inch display is typically 108 ppi. The difference? A little more than 60%. That would account for the 60% difference you see.
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