To call Future methods from Process Builder, call the future method from the in-vocable method. Check the below code for reference.

Sample Code:

public class LightningProcessBuilder {
 
    @InvocableMethod 
    public static void sendEmailToOwner( List < String > listUserNames ) {
 
        callEmailSend( listUserNames );
 
    }
 
    @future
    public static void callEmailSend( List < String > listUserNames ) {
 
        //Write the logic.
       //If it is a call out, use callout = true in future annoation
 
    }
 
}