Для этого можно условно установить maximized
на мобильном телефоне.
Пример -
<q-btn label="Maximized" color="primary" @click="dialog = true" ></q-btn>
<q-dialog
v-model="dialog"
persistent
:maximized="$q.platform.is.mobile?maximizedToggle:false"
transition-show="slide-up"
transition-hide="slide-down"
>
<q-card class="bg-primary text-white">
<q-bar>
<q-space ></q-space>
<q-btn dense flat icon="minimize" @click="maximizedToggle = false" :disable="!maximizedToggle">
<q-tooltip v-if="maximizedToggle" content-class="bg-white text-primary">Minimize</q-tooltip>
</q-btn>
<q-btn dense flat icon="crop_square" @click="maximizedToggle = true" :disable="maximizedToggle">
<q-tooltip v-if="!maximizedToggle" content-class="bg-white text-primary">Maximize</q-tooltip>
</q-btn>
<q-btn dense flat icon="close" v-close-popup>
<q-tooltip content-class="bg-white text-primary">Close</q-tooltip>
</q-btn>
</q-bar>
<q-card-section>
<div class="text-h6">Alert</div>
</q-card-section>
<q-card-section class="q-pt-none">
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</q-card-section>
</q-card>
</q-dialog>
data: function () {
return {
maximizedToggle: true
}
}