StreamingAssets на Android

        string path = "jar:file://" + Application.dataPath + "!/assets/Settings.txt";
        WWW pathWWW = new WWW (path);
        var filepath = string.Format ("{0}/{1}", Application.persistentDataPath, "Settings");
        File.WriteAllBytes (filepath, pathWWW.bytes);
        StreamReader settingsFile = new StreamReader (filepath);

IEnumerator load() {
 
    string filePath = Path.Combine( Application.streamingAssetsPath, "Settings.txt" );
    
    #if UNITY_ANDROID
    UnityWebRequest www = UnityWebRequest.Get( filePath );
    yield return www.SendWebRequest();
    TextBox.text = www.downloadHandler.text;
    #endif
            
}

var lines = textString.Replace( "\r", "" ).Split( new char[] { '\n' }, StringSplitOptions.RemoveEmptyEntries );

string filePath = $"{Application.PersistentDataPath}/Settings.txt"; // с расширением файла!!!
var anyText = "Rus\n0.5\n5";
Encoding utf8WithoutBom = new UTF8Encoding( false ); // кодировка UTF-8 без BOM, чтобы не было "пробела" в начале
using( TextWriter tw = new StreamWriter( filePath, false, utf8WithoutBom ) ) {
    tw.WriteLine( anyText );
}