...
    <el-select
      v-if="props.secondType"
      v-model="modelText"
      placeholder="Выберите предмет"
      @change="changeVal"
    >
      <el-option
        v-for="item in props.secondTypeItems"
        :key="item.id"
        :label="item.value"
        :value="item.id"
      >
        {{ item.value }}
      </el-option>
    </el-select>
    <el-select
      v-else="props.thirdType"
      v-model="modelText"
      placeholder="Выберите активность"
      @change="changeVal"
    >
      <el-option
        v-for="event in props.thirdTypeEvents"
        :key="event.desc"
        :label="event.name"
        :value="event.desc"
      >
        {{ event.name }}
      </el-option>
    </el-select>
...const options = computed(() => {
  if (props.secondType) 
    return props.secondTypeItems.map(({ id, value}) => ({
      label: value,
      value: id 
    }));
  if (props.thirdType) 
    return props.thirdTypeEvents.map(({ desc, name }) => ({
      label: name,
      value: desc 
    }));
  // ...
  return [];
});<el-select
      v-model="modelText"
      placeholder="Выберите предмет"
      @change="changeVal"
    >
      <el-option
        v-for="{ label, value} in options"
        :key="value"
        :label="label"
        :value="value"
      >
        {{ label }}
      </el-option>
    </el-select>