Man pages matching name xcb_randr_get_crtc_gamma_size in section 3:

xcb_randr_get_crtc_gamma_size.3.en	debian 10 / libxcb-doc
xcb_randr_get_crtc_gamma_size.3.en	debian 11 / libxcb-doc
xcb_randr_get_crtc_gamma_size.3.en	debian 12 / libxcb-doc