vue3+elementplus的el-date-picker自定义内容设置如下，利用插槽：

   <el-date-picker
      v-model="searchVal2"
      value-format="YYYY-MM-DD"
      type="daterange"
      range-separator="-"
      start-placeholder="开始日期"
      end-placeholder="结束日期"
      :shortcuts="shortcuts"
    >
      <template #default="cell">
        <div class="cell" :class="{ current: cell.isCurrent }">
          <span class="text">{{ cell.text }}</span>
          <span v-if="isHoliday(cell)" class="holiday">大</span>
        </div>
      </template>
    </el-date-picker>

js：
const searchVal2 = ref("");
const shortcuts = [
  {
    text: "上周",
    value: () => {
      const end = new Date();
      const start = new Date();
      start.setTime(start.getTime() - 3600 * 1000 * 24 * 7);
      return [start, end];
    },
  },
  {
    text: "上个月",
    value: () => {
      const end = new Date();
      const start = new Date();
      start.setTime(start.getTime() - 3600 * 1000 * 24 * 30);
      return [start, end];
    },
  },
  {
    text: "过去3个月",
    value: () => {
      const end = new Date();
      const start = new Date();
      start.setTime(start.getTime() - 3600 * 1000 * 24 * 90);
      return [start, end];
    },
  },
];
const holidays = ["2023-06-01", "2023-06-06", "2023-07-06"];

const isHoliday = ({ dayjs }) => {
  return holidays.includes(dayjs.format("YYYY-MM-DD"));
};

效果图如下：