[Vuejs]-Change the height of v-list-item in v-list-item-group

although this post is old, I hope it still helps you, as I recently needed to set the maximum list size.

<v-list class="max-v-list-height" ...>

<style scoped>
...
>>> .max-v-list-height {
    max-height: 400px;
    overflow-y: auto;
}
...
</style>