I don't believe there's a native way to do this unfortunately. Currently you can only search for other communities (magazines) specific to your kbin instance. As @ChrV noted there are ways to do this via 3rd party
However, once you find a community from another compatible instance you can search for it through kbin.social and subscribe to it. Like searching for "mildlyinfuriating@lemmy.world" without quotes in the search bar will let you subscribe to the mildlyinfuriating community on lemmy.word and the content will show up under kbin.social/sub