Help! Set Variable to Lookup field

[Anonymous]

I have a startup screen which needs to get a field value (LineManager.Email, which for reference is DataCardValue5.AccessibleLabel). However, I need to assign this to a variable field to update a label when the app starts. 

The function works at the minute only if I navigate to the screen in which the LineManager field resides.

Basically, I think I am looking for a Set(Variable,Lookup.... The Lookup I assume might be to the SharePoint List or the PowerApps form I am using?

Any suggestions would be greatly appreciated.

Thanks

[Leo09]

Not quite clear what you need. Why not directly use the DataCardValue5.AccessibleLabel?