const { createApp, h } = Vue;

const Wrapper = {
  props:  {
    name: { type: String, default: "" },
    zIndex: { type: Number, default: 0 },
  },
  setup(props, { slots }) {
    let children = slots.default();
    if (children) {
      for (let i = 0; i < children.length; i++) {
        children[i].props.style = `z-index: ${props.zIndex}`;
      }
    }  
    return () => slots.default()
  }
}

const App = { 
  components:  { Wrapper }
}

const app = createApp(App)
const vm = app.mount('#app')

#app { line-height: 2; }
[v-cloak] { display: none; }

<div id="app" v-cloak>
   <div class="test">
   Test
    <Wrapper name="wrapper1" :z-index="1">
      <img class="picture1" />
      <div class="inner">
        <Wrapper name="wrapper2" :z-index="2">
          <img class="picture2" />
        </Wrapper>
      </div>
      <Wrapper name="wrapper3" :z-index="3">
        <img class="picture3" />
      </Wrapper>
    </Wrapper>
  </div>
</div>
<script src="https://unpkg.com/vue@3/dist/vue.global.prod.js"></script>