Hi @vividichtarosa
This is a kind of lookup question
see the below demo flow to get an idea on how to do this 🙂
Assume i have a form like this

Here user will select the employee id of supervisor and submit it. The supervisor details based on employee id can be found in the below sharepoint list

see the flow

First use the trigger when the form is submitted and use get response details to capture the responses.
2. Next use Get items to the filter the list based on employee id selected

use the Odata filter query to filter the list based on EmpID column (the internal name of EmpID column is Title column as it has been prepared by renaming Title column in my case)
Now use the apply to each to iterate through the results of get items and send an approval request to the email captured via get items like below

Hope this design helps !