I have two envelopes "info " and "reviews"

I wonder if it is possible to add another envelope like "instructions" or something else

or maybe replace "reviews" with something else like "instructions"

Hi, I think perhaps you are referring to the tabs available in the product description, and yes you can add more. Here are the details - https://www.ecommercetemplates.com/help/dynamic-tabs.asp

Thanks,
David