How to modify CX Sales UI layout for Standard & Custom objects

Summary:

How do I modify page layouts (outside of Application Composer) for CX Sales? Do I have to use VisualBuilder for this?

Content (please ensure you mask any confidential information):

HI all,

I am trying to add an extra piece of info in the form of a textbox or label (probably hard coded) on some screens in our CX Sales instance. The layouts I want to do this on include the Service Request Detail layout and others. The use case for the Service Request Detail layout is that we have many versions of this layout that will load depending on the values of the SR (and also the BU/team/role of the currently logged in user). For this reason its not always obvious which layout they're using.