Thanks for the pointer, much appreciated. I scrolled through the list (System > Hardware) and there is an overlay module "rockpi4cplus-usb-host". At least the name suggest it is for this board.
If I toggle this option and reboot, assume it will switch the port from OTG To host mode.
I have the installed community build 24.5.0-trunk.417 Bookwarm.
Radxa official guidance (link) asks to edit /boot/hw_intfc.conf file to change between host & OTG mode.
Armbian build does not have hw_intfc.conf file but I believe /boot/ArmbianEnv.txt is Armbian way to manage the config.
what is the correct way add "intfc:dtoverlay=rk3399-usb-otg" overlay in ArmbianEnv.txt file?