But suppose i have a cone and i want to flip it referencing the plane based on a diagunal face how can i do it?
I hope i explained everything clearly.
Thank you very much in advance!

or you could skip the first move and the ending move is 2x the vector connecting the center of the face to the origin (which is also collinear with the face normal).

Thank you for your reply. I tried with your solution but it doesn’t seem to work.
I put here two screenshot: in the first you can see the wrong result. The face selected is that pointed by the purple arrow. In the second instead you can see the result i would like to obtain.
I hope this explains clearly my situation. Thank you again for any help!

understood. this should have solved for that case.

face normals are in the coordinate space of the mesh’s geometry. if the mesh is in a group that has been translated, rotated, or scale, then this gets a little bit more complicated.