Can the duet of western instruments be regarded as a classical style?

It's hard to say that the playing form and music style are not 100% compatible. For example, the ensemble form of piano and violin can play any style of music, not necessarily classical.

Supplement: the definition of style is a matter for music critics, but it is another matter to be willing to study it. After listening to this song, the arrangement and application of musical instrument melody has a certain classical style, and it can also be said that it draws lessons from some classical music techniques, but overall, the main theme and arrangement are still relatively modern.

In short, for the listener, there is no need to worry too much about style, just like it. Modern music is increasingly manifested in the fusion of various musical styles, such as putting spices in cooking, putting a little bit of this and that, and finally getting the unique taste that the creator wants.