How to export multiple css files with vue-cli?

Hello , how can I export multiple css file when I build my project?
I have multiple theme scss files , I am importing them one by one each time I want to build my project. This is very time consuming. How can I export them seperately when I build my project?

When I build my project , I got this : app.css ,
I want to get this : theme_1.css , theme_2.css , theme_3.css

I get close by using chainWebpack , but this aproach not includes (extract) scss from vue components…

config.entry(‘theme’)
.add(’./src/scss/_theme_1.scss’)
.end();

this my current vue.config.js

module.exports = {
  lintOnSave: false,
  css: {
    loaderOptions: {
      sass: {
        prependData: '\n          @import "@/scss/base.scss";\n        ',
      }
    }
  },

  pluginOptions: {
  },

  chainWebpack: config => {
  config.optimization.delete('splitChunks')
},

  runtimeCompiler: true
}