setPageLayout relies on access to the Nuxt context and can only be called within components' setup functions, plugins, and route middleware.middleware/custom-layout.ts
export default defineNuxtRouteMiddleware((to) => {
// Set the layout on the route you are navigating _to_
setPageLayout('other')
})
If you choose to set the layout dynamically on the server side, you must do so before the layout is rendered by Vue (that is, within a plugin or route middleware) to avoid a hydration mismatch.