Here are a couple ways to regress and progress the traditional planks:
Level 1: Modified Plank - on your knees
Level 2: Plank - keeping your ankle, knee, hips, and shoulders all in alignment
Level 3A: Plank + Arm Raise - try to keep your pelvis level here, AVOID any pelvic rotation
Level 3B: Plank + Leg Raise
Level 4: Bird-Dog Plank 🔥
Alternative: Plank + Military Press = An ultimate Core/Shoulder combination exercise.
💥Fun Fact: The world record for a front plank on elbows was set by a chinese policeman Mao Weidong, who held a plank for 8 hours, 1 minute and 1 second on May 2017 😳