v-focus-directive.vue

<template>
  <div class="cities">
    <div v-for="(city, index) in cities">
      <label :for="'city'+ index">Cidade {{ index + 1 }}</label>
      <input v-focus
        type="text"
        :id="'city' + index"
        v-model="cities[index]"
        placeholder="Insira outra cidade">
    </div>
    <a @click="addCity" href="#">Adicionar outra cidade [+]</a>
  </div>
</template>

<script>

Vue.directive('focus', {
  inserted: (el) => {
    Vue.nextTick(() => {
      el.focus();
    });
  }
});

export default {
  data() {
    return {
      cities: [],
    },
  },
  methods: {
    addCity() {
      this.cities.push('');
    },
  },
};
</script>