Sun Zezhou, chief designer of Tianwen-1, delivered a presentation about China's Mars exploration goals. In it, he gave us some details about the upcoming Tianwen-3 Mars sample return mission.
Tianwen-3 is currently imagined to be a two-launch architecture with a late-2028 launch of a Long March 5 carrying the lander and ascent vehicle, and a Long March 3 carrying an orbiter and return module. Landing on Mars would occur around September 2029 during Martian autumnal equinox in the northern hemisphere, so there may be difficulties with low solar insolation and sand storms. The lander sampling philosophy would resemble a Chang'e 6 style "grab what's near you" set-up with a drill, though potentially carrying a four-legged robot(?) to collect other samples. The ascent vehicle is a two-stage rocket but the details haven't been fully worked out.
The mission would leave Mars in October 2030 and return to Earth in July 2031.