The problem of nuxt Framework of vue

recently I have some problems in learning nuxt server rendering.
1. If you use nuxt for server rendering, according to the official website, create a project framework with create-nuxt-app and then write code there. If you create a project using nuxt scaffolding, you do not need to use create-vue-app or vue init to create a project.
2, If you use create-nuxt-app, how to do server rendering for projects previously created with vue-init or create-vue-app? Copy the file directly?
3. Can multi-page applications do ssr

Dec.23,2021

1.create-nuxt-app creates a complete structural directory
2. The structure is similar and can be copied, but it needs to be modified slightly. For example, asyncData or asycFetch
3.nuxt has both universal and spa modes, and you can do ssr

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