Yes, the tune of the 2023+ Deluxe Air C1-C2 can be changed. The C1 and C2 shocks use different kits.
C1-gen:
11.4118.096.017 REAR SHOCK TUNE ASSEMBLY (INCLUDES SHIMS FOR COMPRESSION TUNE CONFIGURATIONS) - DELUXE AIR C1, (2023-2025)
11.4118.096.018 REAR SHOCK TUNE ASSEMBLY (INCLUDES SHIMS FOR REBOUND TUNE CONFIGURATIONS) - DELUXE AIR C1, (2023-2025)
C2-gen:
11.4118.096.024 REAR SHOCK TUNE ASSEMBLY - COMPRESSION/REBOUND/LOCK(INCLUDES SHIMS FOR COMPRESSION, REBOUND, AND LOCK TUNE CONFIGURATIONS) - DELUXE C2 (2026+)
RockShox service kits and spare parts are best obtained through your local shop or dealer. See our dealer locator, below, to find a dealer near you. If no one is currently listed near you, then please search for local shops via your preferred web browser.
https://www.sram.com/en/dealer-locator
Manuals and additional information about RockShox and SRAM components can be found at our service site, linked below.
https://www.sram.com/en/service
Further questions?
Reach out to Rider Support by Asking A Question at the link below.
https://www.sram.com/en/rockshox/campaigns/rockshox-rider-support