Just for completeness, I used IrScrutinizer to generate a CCF with all 255 discrete codes, and tested them with my 65E6P (2016 LG OLED). This wasn't such a good idea, but I'll get to that shortly. While going through them, I took notes on what I found. In particular, I was looking for two things:

1) Discrete codes to go to specific picture modes (ISF Dark, ISF Light)
2) A code which would show some information about the incoming signal (resolution, frame rate, etc.)

In the end, I found neither. But here's what I did find (all values decimal, and NOT including any that are already described above, unless I noted a difference):

51 - Puts the TV in store demo mode. I'm not sure if this is the same as doing so from the settings menu. It had a neat feature to select which demos to play, and to allow you to load demos from the USB drive as well. Pretty useless though, as it puts the TV in torch mode.

59 - Popped up a box that said "No Options Available"
60 - Same as 59

69 - Seems to do the same thing as 67 (brings up the small settings menu on the right side of the screen)

79 - Show the current input (HDMI1 etc.) in the upper left corner.

83 - (which is listed above as LIST) seems to do the same thing as 76 (CHANNELS)

91 - (which is listed above as EXIT) seems to go to AV input 1. (but that is listed above as 90, so maybe I was off by one here?)

115 - Volume Down
116 - Volume Up
117 - Popup that says "Register Magic Remote"
131 - Popup that says "Only Specific (remotes?) can be paired."
146 - The same as 77 which cycles through picture modes, and is the closest I came to finding the discrete picture modes that I was looking for.
149 - Energy savings
175 - Live Zoom (listed above as well)

181 - Listed above as Recent, and it is...but I don't know if there is any other way to get to this particular feature. I pops up a list of recent things you've done on the TV, a lot like to main "Home" screen", but larger, and only along the bottom of the screen.

187 - Not really documented above, but it is on the list. This is a "Sports Mode" toggle. But, yuck. When you toggle it off, it seems to always revert to "Standard" picture mode? Maybe I had accidentally been in "Standard" when I found this code though? If this interests you, it might be worth checking if it really toggles back to where you were before.

220 - On the list above, but a little hidden. This is the "3d" button.

222 - Popup that says "Register remote"

234 - This one is pretty neat. It pops up a small menu arranged in a circle at the bottom center of the screen that has four options. Power (to turn off the set), Input (to popup the input selection on the right side of the screen), Settings (to jump to the settings), and a selection to leave the "mini-menu."

250 thru 255 *Should not be played with unless you are doing so intentionally"

I didn't know this, but those code are in the range that gives you access to the service menus. Here's how it went for me (for your amusement).

250 - Popup that says "Enter password" (space for 4 digits)
251 - Popup that says "Enter password" (space for 4 digits)
252 - Popup that cycles through different video settings "VidCheck" - So, different values for brightness/color/tint/sharpess. It calls this "P-Check (factory-mode)".
253 - Popup that cycles through differnt sound settings "Sound Check"
254 - Oops. This put me in "Power Only Mode" which is a white screen with instructions on getting out of this mode. I couldn't make it work at first, but eventually I did. I think you press "Back/Exit", and then Power off. But when I powered back on, I was in some other factory mode. And while I was in this mode, the other codes in the 250+ range brought up different service menus. I think what ultimately got out of this mode was when it was telling me to hit "InStop" (Install Stop?), or "InStart" (Install Start?) and realizing that that was probably one of the earlier codes (it is...250 and 251 seem to be InStop and InStart). In the end, this fun excursion did a full factory reset, and I was back to having a brand new TV (which meant I lost my calibration...)

I believe these service menu codes are well documented elsewhere, so please just view my above description solely for amusement. I should go do some research to see how bad my guesses really are. :-)

Other than that, I hope I saved someone some time by going through this exercise.

-Kevin