For the the title and the message you can use:
<style name="MaterialAlertDialog__Center" parent="@style/ThemeOverlay.MaterialComponents.MaterialAlertDialog">
<item name="materialAlertDialogTitlePanelStyle">@style/Title.Panel.Center</item>
<item name="materialAlertDialogBodyTextStyle">@style/Message.Center</item>
</style>
<style name="Title.Panel.Center" parent="MaterialAlertDialog.MaterialComponents.Title.Panel">
<item name="android:gravity">center_horizontal</item>
</style>
<style name="Message.Center" parent="MaterialAlertDialog.MaterialComponents.Body.Text">
<item name="android:gravity">center_horizontal</item>
</style>
with:
MaterialAlertDialogBuilder(this, R.style.MaterialAlertDialog_Center)
.setTitle("Message")
..
.show()
