Custom field ownership switch

Hi SF Community,

I built a custom object titled "Tableau Requests" and I'm looking to have the same structure as my opportunities where I'm able to assign an Opportunity Owner aka Tableau Manager and Notify the user when they get a new Tableau Request. Below are some screenshots of what I would like it to look like:

How do I add the Change feature & the notify user with email

This is what the field looks like currently. 

Thanks!