EPSG/WKID number 4326 relates to WGS84 Geographic, with units in degrees. The ellipsoid is extremely similar to GRS80, with only a slight difference in one of the axes. This is the code and system that the Global Navigation Satellite System (GNSS) is based on (also known as GPS, for the American constellation of satellites). GNSS/GPS satellites are positioned based off of this ellipsoid.
Note that for height values in GNSS or WGS84 data, height is represented as being above or below the reference ellipsoid. In many instances, data provided will reference a GEOID, which incorporates gravitational and terrestrial information and applies a change to the ellipsoid at any given grid position. But EPSG refers simply to the horizontal coordinates, in degree units for WGS84, as the system relates to map projection and coordinate information. Height or elevation values are typically treated separately, even though for data such as GNSS/GPS positioning they're all provided together, and reference the same ellipsoid.
In some instances (I have not encountered such a case), if you need an EPSG that specifically references the vertical dimension above or below the ellipsoid, you can use EPSG 4979 (WKT here). This references the same ellipsoid, but if a Set RSID call needs this dimension, it is included.