@Lolonois It installed. Do i need specific Bios files in a certain directory on the pie as the game kicks right back out, super fast, to ES when i try to launch a game/disk with lr-apple2win.

The cmdline.txt options in the linked topic will only rotate the console terminal, not the entire display. To rotate also EmulationStation's screen or the emulator video output, you need additional configurations - some details are in this topic.

@tyon2006 said in Using HD LCD with Retropie and RPi4:

Makes sense. Any thoughts on retroarch/emulation station supporting these super high resolutions?

If you add a custom hdmi_mode and it's recognized by the Pi4, it should be used automatically.

On the Pi3, I couldnt even get it to boot up all the way

That's normal, since the Pi3 didn't support these large resolutions.

@kikeminchas That's also because of the update - see this post. You can revert the audio to the previous settings by adding snd-bcm2835.enable_compat_alsa=1 to the /boot/cmdline.txt, or modify the .cfg settings file for EmulationStation (as a workaround).