While multipolarity isn't inherently socialist or anti-capitalist, the current/coming form of multipolarity seems to be anti-capitalist, and a pre-cursor to countries becoming socialist.

The primary problem in the world right now, is the Amerikkkan settler-colonialist, white supremacist, fascist global imperialist dictatorship. Every single capitalist country on Earth, knowingly or unknowingly (most of the time, knowingly) is a lapdog of the U.S. or followsd in it's cultural, political, social, and economic footsteps and imperial order.

While capitalism will likely continue to exist even after the U.S. empire falls, the fall of the U.S. will likely be a major death knell or the first major domino of a very long chain of events.

With the largest/most powerful stronghold of capitalism/imperialism being dethroned, as countries across the world are rising up against their neocolonial overlords, and supporting each other, they are and will be increasingly turning towards/socialism, bit by bit.

Rather than being dominated by a single unipolar global dictatorship, multipolarity will mean that the countries/continents of the world will finally have a much larger say in their own affairs, and the institution/enhancement of democracy (actual democracy, not capitalist lies sold as democracy) will mean that socialism will be even more on the rise again.

Nobody (or almost nobody) is inherently/blindly supportive of multipolarity, or multipolarity as an end goal. It's just a major step.

There will no doubt be all kinds of horrific suffering and oppression and death, as human civilization enters a new era. But that will likely, eventually, stabilize.