A standard DRAE 23rd edition (2014) in StarDict format is ~18MB compressed. The should be between 24MB and 29MB. Anything smaller is a stripped-down version.

Understanding StarDict, the DRAE 23ª/24ª Edición, and Dictionary Compression

This article will dissect every component of this search term, explain what makes this file “exclusive,” provide a technical breakdown of the .bz2 compression, and offer a step-by-step installation guide.