You can modify a pose in yoga. That means you make a particular pose more suitable for your body. Every body is different and what works for one person might not work for the other.

You can use yoga blocks or straps to do this, or just do a simpler version of the pose.

Take for example sitting on the floor with your legs outstretched in front of you. It is not possible for everybody to sit like this with a straight back. If you can not sit like this with a straight back, this pose will have to be modified. You are better of sitting on a block to raise your hips, so you are able to sit with a straight back, rather than compromising your posture.