Canon EOS R3 Advanced User's Manual page 458

Case 4: For Subjects That Accelerate or Decelerate
Quickly
Setting to keep tracking and focusing on subjects even if they suddenly change speed.
Effective for subjects having sudden movements, sudden acceleration/deceleration, or
sudden stops.
Note
Try setting [Accel./decel. tracking] to [+2] to keep up with subjects that change
speed significantly from moment to moment (
Default
• Tracking sensitivity: Responsive: 0
• Accel./decel. tracking: +1
458
).