Short answer
Yes, in most of Europe. In my study of 669,760 posts from 112 official party pages in 17 European countries between 2010 and 2020, a typical post by a populist party received about 2.5 times as many likes, comments, shares and reactions as a post by another party of the same size and government status.
What the evidence shows
- The premium was largest for populist radical left parties (about 5.4 times), then populist radical right parties (about 2.3 times) and other populists (about 1.5 times).
- Far-left parties that are not populist showed no premium, and Euroscepticism carried no separate premium.
- It varied a lot by country: large in Spain, the United Kingdom, Norway, Sweden, Hungary and France, and not detectable in Slovenia, Luxembourg, Slovakia, Finland, Greece or Switzerland.
- Bigger audiences explain more than half of it. Populist pages had about 1.9 times the page likes of other parties with the same vote share, but at equal page size a premium of about 1.5 times remained.
- Populist posts drew a higher share of angry reactions (4.4% against 2.7% of interactions).
- There was no detectable change in the premium after Facebook's January 2018 News Feed change.
Caveats
Engagement is not votes. In Scandinavia the radical right's Facebook advantage was a stable feature of how those parties used the platform, not a forecast of their support.