方法一：

// nuxt.config.js
import colors from 'vuetify/es5/util/colors'
import zhHans from 'vuetify/lib/locale/zh-Hans'

export default {
  ……
  vuetify: {
    optionsPath: './plugins/vuetify.js',
      theme: {
        dark: true,
        options: {
          customProperties: true,
        },
        themes: {
          dark: {
             primary: colors.blue.darken2,
             accent: colors.grey.darken3,
             secondary: colors.amber.darken3,
             info: colors.teal.lighten1,
             warning: colors.amber.base,
             error: colors.deepOrange.accent4,
             success: colors.green.accent3,
          },
        },
      },
      lang: {
        locales: { zhHans },
        current: 'zhHans',
      },
      icons: {
        iconfont: 'mdi',
      },
  }
  ……
}

方法二：

// nuxt.config.js

export default {
  ……
  vuetify: {
    optionsPath: './plugins/vuetify.js',
  }
  ……
}

// plugins/vuetify.js
import colors from 'vuetify/es5/util/colors'
import zhHans from 'vuetify/es5/locale/zh-Hans'
export default {
  theme: {
    dark: true,
    options: {
      customProperties: true,
    },
    themes: {
      dark: {
        primary: colors.blue.darken2,
        accent: colors.grey.darken3,
        secondary: colors.amber.darken3,
        info: colors.teal.lighten1,
        warning: colors.amber.base,
        error: colors.deepOrange.accent4,
        success: colors.green.accent3,
      },
    },
  },
  lang: {
    locales: { zhHans },
    current: 'zhHans',
  },
  icons: {
    iconfont: 'mdi',
  },
}

补充nuxt安装Vuetify方法：

Vuetify可以通过添加Nuxt Vuetify模块进行安装。【个人推荐用yarn】

yarn add @nuxtjs/vuetify -D

或者

npm install @nuxtjs/vuetify -D

完成安装后，找到nuxt.config.js文件并打开编辑以添加Vuetify模块到构建中。

// nuxt.config.js
{
  buildModules: [
    // 简单使用
    '@nuxtjs/vuetify',

    // 和选项一起
    ['@nuxtjs/vuetify', { /* 模块选项 */ }]
  ]
}

安装参考网址: https://vuetifyjs.com/zh-Hans/getting-started/installation/#nuxt-5b8988c5

颜色参考网址: https://vuetifyjs.com/zh-Hans/styles/colors/#material-82725f698868

nuxt配置vuetify网址参考：https://go.nuxtjs.dev/config-vuetify