官方文檔沒找到具體的例子，就拼命百度， 終于找到了方法

vue2 mixins封裝

export default {
  data() {
    return {
      pageSize: 20,
      pageNum: 1,
      total: 0,
      pageSizes: [10, 20, 50]
    }
  },
  methods: {
    handleSizeChange(val) {
      this.pageSize = val;
      this.handleCurrentChange(1);
    },
    handleCurrentChange(val) {
      this.pageNum = val;
      this.getList();
    }
  }
};

vue2 .vue 消費組件引入

<script>
import pageMix from '@mixins/page';
export default {
  mixins: [pageMix],
  data() {
    return {
      data: [],
    };
  },
  methods: {
    getList() {
      let query = {
        pageNum: this.pageNum,
        pageSize: this.pageSize,
      };
      // ajax.xxxxx(query).then((res) => {
      //   this.data = res;
      //   this.total = (res || []).length;
      // });
    },
  },
};
</script>

vue3 mixins (返回一個function類型， 可以接收參數(shù))

//mixins/page.js
import { reactive } from "vue"
export default function (getList) {
  const stateData = reactive({
    pageFilter: {
      page: 0,
      size: 10,
    },
    pageConfig: {
      loading: false,
      pageSizes: [10, 30, 50],
      total: 0,
    },
  })
  let handleSizeChange = (val) => {
    stateData.pageFilter.page = 0;
    stateData.pageFilter.size = val;
    getList();
  };
  let handleCurrentChange = (val = 1) => {
    stateData.pageFilter.page = val - 1;
    getList();
  };
  return {
    stateData,
    handleSizeChange,
    handleCurrentChange,
  }
}

mixins 封裝引入消費組件后，yarn serve的時候， 會報錯， 報沒有找到getList方法，因為getList是在消費組件中封裝的方法，mixins/page.js里沒有定義這個方法，這個時候需要傳參

vue3 .vue 消費組件引入 （視覺上更直觀，知道哪些方法或值是從mixins引入的）

<script>
import pageMix from '../../mixins/page.js';
import { reactive, toRefs } from 'vue';
export default {
  setup() {
    let state = reactive({
      filter: {
        keyword:'',
      },
      data:[],
    });
    const getList = () => {
      let query = Object.assign(
        {}，
        state.filter,
        stateData.pageFilter
      );
      query.keyword = query.keyword.trim();
      // ajax.xxxxx(query).then((res) => {
      //   state.data = res;
      //   stateData.pageConfig.total = (res || []).length;
      // });
    };
    const { stateData, handleSizeChange, handleCurrentChange, handleDate } =
      pageMix(getList); // 將mixins/page.js中要用到的方法傳過去
    return {
      ...toRefs(state),
      ...toRefs(stateData),
      handleSizeChange,
      handleCurrentChange,
      handleDate
    };
  },
};
</script>

參考文章
https://blog.csdn.net/amihui/article/details/111632611