How to set SearchView TextSize?

I hope my solution will help(AndroidX).

styles.xml

 <style name="SearchViewStyle" parent="Widget.AppCompat.Light.SearchView">
    <item name="android:textSize">20sp</item>
 </style>

your_layout_name.xml

<androidx.appcompat.widget.SearchView
      app:defaultQueryHint="Search"
      android:theme="@style/SearchViewStyle" // Not style!!
      .
      .
      .
         />

You could do these using code

SearchView searchView = new SearchView(context);
LinearLayout linearLayout1 = (LinearLayout) searchView.getChildAt(0);
LinearLayout linearLayout2 = (LinearLayout) linearLayout1.getChildAt(2);
LinearLayout linearLayout3 = (LinearLayout) linearLayout2.getChildAt(1);
AutoCompleteTextView autoComplete = (AutoCompleteTextView) linearLayout3.getChildAt(0);
autoComplete.setTextSize(60);

Here is another solution

SearchView searchView = new SearchView(context);
AutoCompleteTextView search_text = (AutoCompleteTextView) searchView.findViewById(searchView.getContext().getResources().getIdentifier("android:id/search_src_text", null, null));
search_text.setTextColor(Color.WHITE);
search_text.setTextSize(TypedValue.COMPLEX_UNIT_PX, getResources().getDimensionPixelSize(R.dimen.text_small));

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"/>