Are the major sins limited to the seven destructive ones, or are they more numerous, or are the seven destructive ones the most egregious among them?

Major sins are not limited to seven; rather, the seven were singled out due to their heinousness. It has been reported from Ibn Abbas that they are closer to seven hundred. The Prophet’s (peace be upon him) statement, "Major sins are seven," refers to some of the major sins, not an exhaustive list. This indicates that what is meant is a portion of them, and major sins multiply with the multiplicity of hadiths that mention them.