What is the max altitude where the worst weather phenomena shapes?Can commercial airliners?

Question

fly over it?

Answer 1

LOOK UP TROPOSPHERE. AND tropopause

Yes, when pilots are flight planning for a plane that is capable, the pilots inquires  as to where the "trop" is and might plan to fly above it.

the poster below is referring to Cumulonimbus Incus  an enormous towering mass of cloud, which can grow to an incredible 60,000 feet.  It is very rare. most thunderstorms max out at about 35K feet

You go WAY around these not over.

Answer 2

Radar summary charts show echoes from towering cumulus clouds at FL 670.  And higher.  Commercial airliners can't fly over that.