// child.vue
// script setup
...
const value = defineModel('value')
const count = defineModel('count')
// const ... = defineModel(...)
...

<script setup>
const data = reactive({value: 'abc', count: 4})
</script>
<template>
 <child v-model:value="data.value" v-model:count="data.count" />
</template>

// father.vue
<script setup>
const origin = reactive({ name: 'ww' })
const data = toRefs(origin)
</script>
<template>
 ...
 <child v-model="data" />
 ...
</template>
// child.vue
<script setup>
...
const model = defineModel()
...
</script>
<template>
 ...
 <input v-model="model.name">
 ...
</template>

// father.vue
<script setup>
const origin = reactive({ name: 'ww' })
const data = reacitve({ origin })
</script>
<template>
 ...
 <child v-model="data" />
 ...
</template>
// child.vue
<script setup>
...
const model = defineModel()
...
</script>
<template>
 ...
 <input v-model="model.origin.name">
 ...
</template>

// father.vue
<script setup>
const data = ref({ name: 'ww' })
</script>
<template>
 ...
 <child v-model="data" />
 ...
</template>
// child.vue
<script setup>
...
const model = defineModel()
const name = computed({
 get: () => model.value.name,
 set(val) =>model.value = { ...model.value, name: val }
})
...
</script>
<template>
 ...
 <input v-model="name">
 ...
</template>