The claim does not specify whether it refers to the EU or Europe as a whole. France is the 3rd largest economy in Europe by nominal GDP (after Germany and the United Kingdom), but 2nd largest within the EU-27.
The UK economy has been larger than France's since approximately 2022-2023, with a GDP of approximately $5.2 trillion compared to France's $4.0 trillion (nominal GDP, 2024 data).
Sources are from Wikipedia (secondary source citing IMF data) as direct Eurostat comparisons including non-EU countries like the UK were not immediately available.
Sources
PrimaryEurostat - National accounts and GDPIn 2024, the 4 largest EU economies (Germany, France, Italy and Spain) accounted for just under three fifths (59.1%) of the EU's GDP
SecondaryStatista - GDP of European countries 2024The similarly sized economies of the United Kingdom and France were the second and third largest economies in Europe during this year