Sort of. 32 bit internally, 16 bit externally. Not as fast as the DX but had all the processor modes so could run protected mode unlike the 286.

One place I worked we sold a 286 upgrade board that had a 386sx and a few support chips. Undearneath was a 286 style socket. You removed your 286 and put this thing in its place. They worked OK and provided a decent speed boost.

Amstrad's last great PC series (the 3x86 series made with very standard components, unlike the unusual 2x86 series) used this strategy for the 3386, I think.

The 286 is a 16-bit CPU, whereas the 386 is 32-bit CPU.

This alone made the 386 far more capable and compatible with modern software (Linux requires 32-bit).