Hi @Maria the short answer is no. If you introduce GCP's they will assist placing your results at the "correct" height. Esri is planning for Site Scan to use the "reprojection engine" which includes support for many vertical datums. A much wanted upgrade.
It would be nice to have NAVD88 for the SLP. Additionally, even when ft are selected for the project the GCP elevations are forced to meter. This adds confusion and reprocessing if one forgets to convert.
@TylerIzzi, what is the SLP? The unit used for the GCPs is defined by the selected horizontal coordinate system. You can choose to set your project to a different unit and that unit will be used in the map view.
