Microchip MPLAB Harmony provides several application examples for most supported peripherals and device families. See the following repositories under Microchip-MPLAB-Harmony Github project for specific applications examples:

Repository	USB functionality
usb_apps_device	Application examples for USB Device functionality
usb_apps_dual_role	Application examples for USB Dual Role functionality
usb_apps_host	Application examples for for USB Host functionality
usb_apps_multi_controller	Application examples for for USB Multi Controller functionality