that is the definition of first strike capability though. Hit the enemy so hard, and more importantly accurate, that it makes their retaliation either impossible or greatly reduced to a point where you deem acceptable. It's just a capability that's very hard to achieve, but if theoretically performed, it would be a preemptive surprise counterforce strike towards all of the enemy's nuclear weapons to ensure they cannot retaliate.
The reason MAD works is that currently no one possesses absolute first strike capability, so no one strikes first. In any case I feel like China should pursue first strike capability if it wants to become the dominant superpower