No GCP Pro converts your EPSG: 3753 to the appropriate WGS 84 UTM zone, which for most of Ohio is WGS84 UTM 17 N, which I think is EPSG:32617. ODM performs all calculations using the local UTM zone. It’s standard output is in WGS84 UTM. To get the output in another projection, go to the View Map screen of WebODM. there is a button in the upper right hand corner, it’s the Layers button. You can re-project and export the orthos or dems and into EPSG 3753. It will re-project and download.