Sitting cross-legged is an important part of yoga practice and is commonly used for breathing and meditation practices. It requires flexibility in the back thighs, back of the pelvis, and inner thighs, as well as external rotation of the hip joints. These are all very strong muscles that can take a long time to stretch. Whether you sit in a simple cross-legged posture like Sukhasana or a more difficult pose like Padmasana (Lotus Pose), developing the flexibility to sit easily is a gradual process.
it’s important to note that everyone has a different anatomical structure in their hips, which may potentially inhibit this kind of movement. If this is the case for you, then trying to work up to Padmasana (Lotus Pose) is an inappropriate goal. I encourage you to try other poses that may be more comfortable, like Vajrasana (Thunderbolt Pose), sitting on your heels, Virasana (Hero Pose), sitting between your heels, or Gomukhasana (Cow Face Pose). You can also meditate sitting on a chair. The chair should be firm, your back straight, and your feet on the floor or supported on a book or cushion.