vue3子组件如何修改父组件传过来的props数据

<ChildComponent v-model:test="test" />

<ChildComponent :test="test" @update:test="test = $event" />

//ChildComponent 
   props: {
    test:String     //接收父组件数据
  },
  emits: ['update:test'],      //定义组件可触发的事件
  setup(props,ctx){
    function onClick() {
      ctx.emit('update:test','child')
    }
  }

<ChildComponent :obj="obj" @update:obj="updateObj" />

const obj = reactive({
  key: 'test'
})

function updateObj(params){
  obj.key = params
}
return{
  updateObj
}

//ChildComponent 
   props: {
    obj:Object     //接收父组件数据
  },
  emits: ['update:obj'],      //定义组件可触发的事件
  setup(props,ctx){
    function onClick() {
      ctx.emit('update:obj','child')
    }
  }