Yes, replacement upper tubes are available for the 2019 Boxxer C1.
Right:
11.4018.093.000 FORK CSU UPPER TUBE - TAPER WALL, RIGHT, BLACK - BOXXER C1-C2 (2019-2023)
Left:
11.4018.093.001 FORK CSU UPPER TUBE - TAPER WALL, LEFT, BLACK - BOXXER C1-C2 (2019-2023)
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