Personally if I were to write a magician as the main character I would reveal to the reader how the trick works because I can imagine how frustrating it would be to not know as a reader. However I do think it’d be really fun to hide how it works at first and reveal it later perhaps in the form of a conversation with a friend after a show or as an inner dialogue

However if the magician is not the main character I would not directly reveal the trick but imply it through the narrators thoughts or conversation with other characters, make it feel as of the main character themselves is trying to figure out how it worked to guide the reader along but not directly state the trick.

Moreover if the magician is actually using magic that much should be clear to the reader. If the trick is impossible without some real magical help that magic system should be known to the reader before the show/trick or the show/trick should be the reveal of that magic system in some way

I’m no writer so take this with a grain of salt of course but I do love to read and I can imagine situations where I might get frustrated or confused with an authors writing.

Sidenote, I’d love to hear more about whatever you’re writing ;)