Small font print command for Bluetooth printer - xamarin

Question

I'm working on the Bluetooth thermal printer implementation in Xamarin android,
Where i'm able to reset the printer and add the three additional lines using the print commands, but facing problem in reset the fonts to smallest size.
I'm resetting the printer using command "btInitialise"then trying to set small fonts using command "btFontB" and then adding 3 blank additional lines using "btAdvance3Lines".
The command in "btFontB" is not working properly or the command is wrong or the way i'm trying to achieve is wrong. A help will be appreciated here.
using (BluetoothAdapter bluetoothAdapter = BluetoothAdapter.DefaultAdapter)
{
BluetoothDevice device = (from bd in bluetoothAdapter?.BondedDevices where bd?.Name == deviceName
select bd).FirstOrDefault();
try
{
using (BluetoothSocket bluetoothSocket = device?.
CreateRfcommSocketToServiceRecord(
UUID.FromString("00001101-0000-1000-8000-00805f9b34fb")))
{
if (bluetoothSocket == null)
return;
string btInitialise = "\x001b\x0040\n";
string btFontB = "\x001b\x0021\x0000\n";
string btAdvance3Lines = "\x001b\x0064\x0003\n";
await bluetoothSocket.ConnectAsync();
byte[] resetPrinter = Encoding.ASCII.GetBytes(btInitialise);
await bluetoothSocket.OutputStream.WriteAsync(resetPrinter, 0, resetPrinter.Length);
byte[] setFont = Encoding.ASCII.GetBytes(btFontB);
await bluetoothSocket.OutputStream.WriteAsync(setFont, 0, setFont.Length);
byte[] buffer = Encoding.UTF8.GetBytes(text);
await bluetoothSocket.OutputStream.WriteAsync(buffer, 0, buffer.Length);
byte[] addLines = Encoding.ASCII.GetBytes(btAdvance3Lines);
await bluetoothSocket.OutputStream.WriteAsync(addLines, 0, addLines.Length);
}
}
catch (Exception exp)
{
throw exp;
}
}