Front planks aren't anything new. Still, most people butcher them because they lack body position awareness.
Putting the feet, especially the heels, against the wall provides a tactile reference point to activate the hamstrings and hold the pelvis in position against gravity.
Start on your elbows and knees with your feet pressed flat against a wall. Walk your arms out until your elbows are 1-2 inches in front of your shoulders to create a long-levered plank.
Drive your heels into the wall and, with your hamstrings, contract your torso towards your feet. Imagine you're pulling your back pants pockets to the back of your knee.
Push your elbows through the ground, raising the upper back toward the ceiling and creating a hill instead of a valley between the shoulder blades.