If you performed the technique correctly and they perform their technique incorrectly, even then it's unlikely but the leg can break. But that's a whole lot of ifs. It'll be best to count on it not happening ever.
If I'm an inexperienced fighter, then how can I even do a "muay thai" block?
I don't know what a muay thai block is. But any block in any self-defense can be used as a strike. How well you are conditioned, and how well (or how poorly) your opponent is, will determine whether that block/strike can "break a leg".
If by "break a leg" you mean to break a bone, like the femur or shin, then it is highly unlikely. But if you mean to disable it, by way of the joint, a nerve strike, or a lock, then yes, it is definitely possible. But such things require practice, and it is not likely that an inexperienced fighter can do this effectively.
Yeah i'd break the leg with a gun. Then break into his chest w/ two .45 slugs
Pretent you are unexperience fighter what if an attacker give u a low kick and u do a muay thai block all of a sudden can the attacker leg be broken?