I have a 10 meter cell size Oregon DEM that I would like to match my Northern California DEM thats at a 30 meter cell size.
How would I go about changing the Oregon DEM cell size from a 10 meters to 30 meters using ArcGIS Desktop 10.5?
I believe by extent you mean the raster cell size. According to ESRI Altering The Resolution you have two options.
I also believe it is possible to simply export the current 10x10 raster to a 30x30 raster by simply changing the cell in the export popup window (see image below). But I am not sure how this aggregates the data.