sharepoint server – Configure search service to search only by pages content excluding CreatedBy(Aurhor field)

I have several Search Result Sources configured in CA.

For example result source Documents(search by documents) and Pages(search by Pages content type).

I have custom spfx search results web part.
Web part sends 2 REST API requests to search service including sourceId(sourceId=Result source guid) property.

I need search by CreatedBy field in Documents area and I don’t need search by CreatedBy in Pages area.

There are hundred of sites and webs.

How I can achieve this? – Search by CreatedBy for Documents result source and Search only by page content for Pages result source.

UPD. I tried to manipulate selectProperties parameter but it wasn’t helpful.