When I use npm i react-native-bootsplash, to remove default one I use below code

<item name="android:windowIsTranslucent">true</item>

<resources>

    <!-- Base application theme. -->

    <style name="AppTheme" parent="Theme.AppCompat.DayNight.NoActionBar">

        <!-- Customize your theme here. -->

    </style>

    <!-- BootTheme should inherit from Theme.BootSplash or Theme.BootSplash.EdgeToEdge -->

    <style name="BootTheme" parent="Theme.BootSplash">

        <item name="bootSplashBackground">@color/silver</item>

        <item name="bootSplashLogo">@drawable/ic_launcher</item>

         <!--<item name="bootSplashBrand">@drawable/ic_launcher</item> Only if you have a brand

        image -->

        <item name="android:windowIsTranslucent">true</item>

        <item name="postBootSplashTheme">@style/AppTheme</item>

    </style>

</resources>