Sigma released the results of some comprehensive testing it did with its lens lineup and the new Canon R5 and R6 cameras. The upshot: if you have Art lenses that have had their firmware updated since 2017, you’re good.
Sigma recommends turning off Digital Lens Optimizer (DLO), and turning on the individual correction elements, such as those for vignette, chromatic aberration and distortion.
Autofocus can be used within an area excluding about 10 percent of the distance from edge to edge on all four sides.
Lens stabilization (Sigma calls this OS) won’t work on lenses that have been set via their dock to full-time manual focus. The in-camera “IBIS” stabilization will work well only for lenses in the Art, Sport or Contemporary lines.