Has there ever been a 11–1 in the La Liga?

Yes, 1 time.

The only time: September 29, 1940, Sevilla FC beat FC Barcelona (Sevilla FC 11–1 FC Barcelona).

Nearby scores

1. 12–0 Never
2. 12–1 1 time
3. 12–2 Never
4. 11–0 Never
5. 11–1 1 time
6. 11–2 1 time
7. 10–0 3 times
8. 10–1 5 times
9. 10–2 1 time