Try define a different style in the styles.xml and set the first with the textSize 30sp and the second with 24sp
<style name="title">
<item name="android:textSize">30sp</item>
</style>
<style name="summary">
<item name="android:textSize">24sp</item>
</style>
and set the style using the lines where you want to use.
style="@style/title"
or
style="@style/summary"
I hope this helps.