The Talmud (Chullin 5a) states:
לימא מסייע ליה והעורבים מביאים לו לחם ובשר בבקר ולחם ובשר בערב ואמר רב יהודה אמר רב מבי טבחי דאחאב על פי הדבור שאני
Can we say that the following supports his [R. ‘Anan's] view? It is written: And the ravens
brought him bread and flesh in the morning, and bread and flesh in the evening, and Rab Judah
Eliyahu at Har Carmel. Standard halachic opinion is that sacrifices away from the Temple were forbidden. So Eliyahu was either directly told to break this, or decided on his own and that decision was then endorsed by the resulting fire.
Rambam seems to understand the first way. See the Hilchos Yesodei HaTora 9:3 where he says that Eliyahu was acting under ...
Hashem tells Yechezkel that his wife is going to die, and that he specifically shouldn't observe several of the practices of aveilus (Yechezkel 24:16-17). It's a machlokes whether the first day's aveilus is Min Hatorah or Miderabanan (Shulchan Aruch Yoreh Deah 398), but either way these laws are part of Torah.