Can you change from regular mower blade to mulching mower blade?

yes

A regular blade is typically sharpened only near the end with a bend at the tip to increase the airflow. A mulching blade is sharpened from the end towards the middle and has multiple cutting angles which aid in cutting the grass multiple times into smaller pieces. The better mulchers also include a discharge plug which forces the grass to be cut into fine particles. When changing blades always make sure the length is the same and that the mounting holes match the original.