Convert GeoTIFF height map to raw file for Unity terrain

I have a GeoTIFF file that QGIS has produced from merging multiple DEM TIFFs together. The gdalinfo for this file is:

Driver: GTiff/GeoTIFF
Files: ca_heightmap.tif
Size is 39601, 39601
Coordinate System is:
GEOGCRS["WGS 84",
    DATUM["World Geodetic System 1984",
        ELLIPSOID["WGS 84",6378137,298.257223563,
            LENGTHUNIT["metre",1]]],
    PRIMEM["Greenwich",0,
        ANGLEUNIT["degree",0.0174532925199433]],
    CS[ellipsoidal,2],
        AXIS["geodetic latitude (Lat)",north,
            ORDER[1],
            ANGLEUNIT["degree",0.0174532925199433]],
        AXIS["geodetic longitude (Lon)",east,
            ORDER[2],
            ANGLEUNIT["degree",0.0174532925199433]],
    ID["EPSG",4326]]
Data axis to CRS axis mapping: 2,1
Origin = (-125.000138888888998,43.000138888888898)
Pixel Size = (0.000277777777778,-0.000277777777778)
Metadata:
  AREA_OR_POINT=Area
Image Structure Metadata:
  INTERLEAVE=BAND
Corner Coordinates:
Upper Left  (-125.0001389,  43.0001389) (125d 0' 0.50"W, 43d 0' 0.50"N)
Lower Left  (-125.0001389,  31.9998611) (125d 0' 0.50"W, 31d59'59.50"N)
Upper Right (-113.9998611,  43.0001389) (113d59'59.50"W, 43d 0' 0.50"N)
Lower Right (-113.9998611,  31.9998611) (113d59'59.50"W, 31d59'59.50"N)
Center      (-119.5000000,  37.5000000) (119d30' 0.00"W, 37d30' 0.00"N)
Band 1 Block=39601x1 Type=Float32, ColorInterp=Gray

How can I convert this to a raw file that I am able to import as a terrain in Unity? When I open this TIFF in GIMP, I just get a black/white image that loses the height map aspect (I’m not really sure what happens to it, but it looks like this in GIMP)