You likely can upgrade your current 8, 9, 10, or 11-speed equipped bicycle, provided you have a rear wheel with an XDR driver body.
Replacement XDR driver bodies are available from most wheel manufacturers to retrofit 11-speed road rear hubs. If you currently have an 8, 9 or 10-speed drivetrain, upgrading your wheelset or rear hub to one that incorporates compatibility with an XDR driver body will allow you to install an eTap AXS groupset to your bike.
To verify if your hub is XDR driver compatible, contact your hub manufacturer to verify if they produce a compatible XDR driver for your specific hub. The SRAM version XDR drivers are compatible with SRAM hubs only. Many hub manufacturers currently offer XDR compatible drivers for their hubs.
If your frame is not equipped for flat mount disc brakes, Rival eTap AXS is not compatible as it is offered in a flat mount disc brake only option. There is a SRAM RED eTap AXS post mount disc caliper option and hose kit that is available separately. Both SRAM RED and Force eTap AXS offer a mechanical rim brake option as well.