Thrawn figured out Kallus was a Rebel Spy even though Lyste was accused of being Fulcrum. Thrawn figured Kallus out RIGHT after Lyste was arrested, and Thrawn did it with a PAINTING, ain't NO way you can fool him.

Thrawn did it … in a CAVE … with a box of scraps!!!

Lol

That's an Iron Man reference?

Yes

Only if he doesn't know anything about you or what you're lying about. But he'd likely investigate if it's true, so....

Well…he did ultimately answer to Palpatine lol

He's not omnipotent. It's possible, but you know the saying: fool me once, shame on you, fool me twice, shame on me.

Fool Thrawn once, death on you. There's no second chance to fool him.

^ to be a bit more serious, Omega has a very good point. Sometimes Thrawn would lose a tactical battle and even let the enemy “get away” from him, but he uses that experience to learn about his enemy.

Thus if you lie to him he will either eventually discover your lie, or he will know you are lying and let you think you are getting away with it, just so he can learn more about you so that he knows what to expect next time.

I think back to A New Hope where Leia gives the location of the Rebel base as Dantooine to Tarkin. He seems to take this seriously with the "She lied to us!". I can imagine Thrawn would have in the back of his mind that Leia would lie or may indeed not send anyone to Dantooine at all. I think he could be lied to in canon, but it wouldn't be easy. Also thinking back to Legends and what happened there which shows Thrawn is not immune to deception.

I would say no because especially if one is lying to him to his face, it wouldn't work because Chiss see infrared, and he is trained to see heat signature changes.