You can add a configuration that is the duplicate of an existing one and then make edits to it.
One reason to make a duplicate configuration is to create your own debug configuration. Although MPLAB X IDE provides debug macros for use with Microchip tools (see “Debug Macros Generated” in Debug Code), you may want to use your own debug macros or you may want to set up the same debug capabilities with third-party tools.
To set up a debug configuration:
To use macros in code to switch to other configurations, like debug, see Configuration Macros.