Thanks for the question.
While it may not be a sin to see this movie (like other fantasy films that have magic wielding characters), or even to watch it again, it may be prudent to avoid it, simply from the standpoint that the makers of these movies tend to push the limit further and further toward darkness.
- If there is plenty of financial support to do so, why would they stop?
They often have a dark agenda and these days the entertainment industry cannot be trusted, especially when companies like Disney explicitly state their intent to add content to change the our current culture. (You may be aware of these goings on recently in the state of Florida.)
Other film patrons, who are not so discerning, may be harmed by the temptation to dabble in "black magic" or have some other negative outcome that does not serve God.
As I get older, I find it more obvious that the content produced by Hollywood, the networks, and cable conglomerates is mostly anti-Christian in its world view, and in some cases diabolical. Be prepared to shut it all off if necessary. Better to enter Heaven with one eye than to enter Hell with two, or in this case with one (holy) entertainment outlet than all the diabolical traps that are put out before us.
So the bottom line, it is not a sin yet, but keep your guard up.