If the Company upgrades to the QBO Advanced. Would I be able to customize users to allow them to be able to upload receipts and track their mileage?

Hey there khrystal-riggs-f,

It's always a pleasure to see new faces in the Community, Welcome! It's important to know the user roles and limitations for the subscriptions you may have. This helpful guide will explain how to add and manage custom roles in QuickBooks Online Advanced. In addition, here is an article on User roles and access rights.

If you require further assistance, I recommend reaching out to the support team outside of the Community. With your permission, they'll be able to view your screen to better assist you. Here are a few ways you could reach them. 

Schedule a Callback or start a Chat: click (?)Help in the upper right > type and enter "Contact support" into the QB Assistant > click Contact Us > explain your situation > click Let's Talk > choose Get a callback or Start a Chat.
Social Media: Facebook and Twitter

If you have any other questions, feel free to reach out here.

@khrystal-riggs-f 

You need a 3rd party app to do so.