File Size after Conversion to TIF From CR3

@Tomasese 

Raw files are generally a single grayscale channel (if using say a Bayer mosaic camera sensor) and 12-14 BPC, when they are processed into a rendered image they are then three channel RGB and 16 BPC. This will have an open size in memory, however, when saved the file on drive may be smaller due to file format options such as lossy or lossless compression.

TIFF and PSD are generally the largest file formats, you can use various types of compression if you need smaller files. But JPEG will usually be smallest and then RAW files, and then a TIFF or PSD. This sounds normal.