App.vue
ChildComp.vue
main.js
 
<template>
  <h2>Example Built-in 'is' Attribute</h2>
  <p>The IMG tag below is set to be replaced by a component by the use of 'is="vue:child-comp"'.</p>
  <img is="vue:child-comp" />
</template>                  
<template>
  <div>
    <h3>ChildComp.vue</h3>
    <p>This is the child component</p>
  </div>
</template>

<style scoped>
div {
  border: solid black 1px;
  background-color: lightgreen;
  padding: 10px;
  max-width: 250px;
  margin-top: 20px;
}
</style>                  
import { createApp } from 'vue'

import App from './App.vue'
import ChildComp from './components/ChildComp.vue'

const app = createApp(App)
app.component('child-comp', ChildComp)
app.mount('#app')
                  
http://localhost:5173/