I think that if OP finds The Matrix too adult, Ex Machina is even less appropriate.

Her is a good recommendation but I struggle to imagine a 12 year old identifying well with alienated-middle-aged-man-malaise ;) (although I loved Lost in Translation at 14 or so)

Arrival is a great recommendation. I had some quibbles with its science, but it’s good Sci Fi. Then he can introduce him to Ted Chiang’s other writing

Ex Machina has some nudity, but less gun violence? It’s a lot more idea driven than action/violence driven (matrix). And the themes are different. Depends on what people culturally mean as adult I suppose.

Its been a while, but isn't the main theme sexual slavery? I could understand why people consider that adult.

I admittedly don't have kids, but media is so saturated and oversexualized that I personally feel that thought-provoking fiction that dissect and critique urges are possible and good to explore at some point, in safe company accompanied with brief discussion. I'm certainly thankful I got offered these discussions in safe ways.

That said, Ex Machina might be a little intense in that regard, even though I seem to remember that the explicitly is mostly some nudity. It's a great movie, but probably not the first or fifth I would show a 12-year-old with the above discursive parameters included.

Perhaps the tenth or a six months on of watching and discussing movies and their depiction of life in an open way.

Not really? Main theme is a general intelligence that’s not aligned with you may trick or deceive you.

Not sure about Ex Machina for a 12 y/o:

https://www.imdb.com/title/tt0470752/parentalguide

I also seem to recall that Her was thematically aimed at adults.

Wasn’t there any entire scene where he jerks off while she talks dirty to him? Maybe I’m misremembering or its another movie.

No, that’s some other movie.

It's been too long since I saw Her to remember the particulars, but the IMDB Parents Guide for it contains an entry that backs Pigalowda's comment.

https://www.imdb.com/title/tt1798709/parentalguide

Parents Guide for Her:

https://www.imdb.com/title/tt1798709/parentalguide

OP should probably consult the IMDB Parents Guide for all of these. Everyone has their own ideas about what's okay for kids and what's not.

I was confused about the movie you were talking about - in “her” yeah there’s this scene, but the screen is black (and it’s more uncomfortable than anything else).

Parent can always watch first. 12yo is middle school right? 8th grade? I doubt this would be a 12yr olds first exposure to this kind of thing (and the context of the movie’s story is not a bad place for it).

Rereading the OPs request they mention “adult language” in the matrix so you’re probably right that my recs won’t be a good fit.

Ex Machina is rated R. It's a great movie but the language, nudity, and sexual content might not be appropriate for a 12 year old.

Your 12yo will look at Asian chicks a lot differently after Ex Machina.