Holy See (Vatican City) is about 17,793 times smaller than French Southern and Antarctic Lands.

French Southern and Antarctic Lands is approximately 7,829 sq km, while Holy See (Vatican City) is approximately 0 sq km, making Holy See (Vatican City) 0.01% the size of French Southern and Antarctic Lands.
Tip: This to-scale comparison of French Southern and Antarctic Lands vs. Holy See (Vatican City) uses the Mercator projection, which distorts the size of regions near the poles.
Compare further: Holy See (Vatican City) vs. French Southern and Antarctic Lands