If you’re looking to make this exercise easier, you could try something like knee catches or single leg stretch variations. With knee catches, you’ll stack your knees over your hips at a 90-degree angle, and then alternate hovering one foot down at a time while engaging the core. With single leg stretch variations, you set up the same way you do for knee catches, but instead of alternating hovering the feet, you alternate extending the legs out straight at a 45-degree angle.
To make leg lifts more challenging, you can try V-ups, which add an upper body challenge to the leg raise movement. As you lift the legs, you also perform a sit up, extending your arms up straight toward your feet. If you have access to a workout bar, you can try hanging leg raises, as well.
You can also add ankle weights, to test your core strength even more. For a different challenge, you could place a block or a mini exercise ball between your thighs or ankles—this will help target and engage your thigh muscles, too, particularly your abductors.