用vue3和elementPlus写一个下拉多选并且支持可输入的组件，输入框后面需要一个+图标，点击这个图标后下拉选项就显示出来

好的，这是一个比较简单的组件，以下是代码示例：

<template>
  <el-select
    v-model="selectedOptions"
    multiple
    filterable
    remote
    reserve-keyword
    :remote-method="remoteMethod"
    :loading="loading"
    :placeholder="placeholder"
    @focus="handleFocus"
  >
    <template #prefix>
      <i class="el-input__icon el-icon-search"></i>
    </template>
    <el-option
      v-for="item in options"
      :key="item.value"
      :label="item.label"
      :value="item.value"
    ></el-option>
  </el-select>
</template>

<script>
import { ref } from 'vue';
import { ElSelect } from 'element-plus';

export default {
  name: 'MultiSelect',
  components: {
    ElSelect,
  },
  props: {
    options: {
      type: Array,
      default: () => [],
    },
    placeholder: {
      type: String,
      default: '请选择',
    },
  },
  setup(props) {
    const selectedOptions = ref([]);
    const loading = ref(false);

    const remoteMethod = (query) => {
      loading.value = true;
      setTimeout(() => {
        loading.value = false;
        const filteredOptions = props.options.filter((option) =>
          option.label.toLowerCase().includes(query.toLowerCase())
        );
        filteredOptions.length > 0
          ? (this.options = filteredOptions)
          : (this.options = props.options);
      }, 200);
    };

    const handleFocus = () => {
      if (selectedOptions.value.length === 0) {
        remoteMethod('');
      }
    };

    return {
      selectedOptions,
      loading,
      remoteMethod,
      handleFocus,
    };
  },
};
</script>

<style scoped>
.el-input__icon {
  color: #c0c4cc;
}
</style>

这个组件使用了 Element Plus 的 `el-select` 组件，支持多选、可输入、远程搜索等功能。在输入框后面添加了一个搜索图标，点击图标会触发下拉选项的显示。