I am currently working on a spreadsheet that lists 19 stores and within those
19 stores there is a list of employees that I would like to be able to expand
in and out as data is needed to input for those employees. How can I get the
rows to expand under each store by clicking on the plus symbol to the left of
the store? I have seen it done just never did it myself.

[+] Store 001
Employee 1
Employee 2
Employee 3

This is roughly how I envision it. Thank you for your help!