How to set SearchView TextSize?

You can achieve this using a theme:

in styles.xml

<style name="AppSearchView" parent="Widget.AppCompat.SearchView" >
        <item name="android:textSize">60sp</item>
    </style>

And using a SearchView

<android.support.v7.widget.SearchView
            android:id="@+id/searchView"
            android:layout_width="350dp"
            app:theme="@style/AppSearchView"
            android:layout_height="80dp"
            android:layout_marginTop="15dp"/>