Here is the code:

#include "BluetoothSerial.h"

BluetoothSerial SerialBT; // Object for Bluetooth

void setup() {
Serial.begin(115200); // Start the built-in serial port, possibly to communicate with the host computer
//SerialBT.begin("ESP32test"); // Start BluetoothSerial with the name "ESP32test"

Serial.println("Bluetooth device is ready to pair");
}

void loop() {
if (SerialBT.available()) { // Check if we receive anything from Bluetooth
Serial.write(SerialBT.read()); // Send what we receive to the built-in serial port
}

if (Serial.available()) { // Check if anything is coming from the built-in serial port
SerialBT.write(Serial.read()); // Send what we receive to Bluetooth
}
}

Here is the error:

c:/users/talha/appdata/local/arduino15/packages/esp32/tools/xtensa-esp32s3-elf-gcc/esp-2021r2-patch5-8.4.0/bin/../lib/gcc/xtensa-esp32s3-elf/8.4.0/../../../../xtensa-esp32s3-elf/bin/ld.exe: libraries\BluetoothSerial\BluetoothSerial.cpp.o:(.literal._ZL8_stop_btv+0x18): undefined reference to esp_spp_disconnect' c:/users/talha/appdata/local/arduino15/packages/esp32/tools/xtensa-esp32s3-elf-gcc/esp-2021r2-patch5-8.4.0/bin/../lib/gcc/xtensa-esp32s3-elf/8.4.0/../../../../xtensa-esp32s3-elf/bin/ld.exe: libraries\BluetoothSerial\BluetoothSerial.cpp.o:(.literal._ZL8_stop_btv+0x1c): undefined reference to esp_spp_deinit'
c:/users/talha/appdata/local/arduino15/packages/esp32/tools/xtensa-esp32s3-elf-gcc/esp-2021r2-patch5-8.4.0/bin/../lib/gcc/xtensa-esp32s3-elf/8.4.0/../../../../xtensa-esp32s3-elf/bin/ld.exe: libraries\BluetoothSerial\BluetoothSerial.cpp.o: in function _stop_bt()': C:\Users\Talha\AppData\Local\Arduino15\packages\esp32\hardware\esp32\2.0.14\libraries\BluetoothSerial\src/BluetoothSerial.cpp:714: undefined reference to esp_spp_disconnect'
c:/users/talha/appdata/local/arduino15/packages/esp32/tools/xtensa-esp32s3-elf-gcc/esp-2021r2-patch5-8.4.0/bin/../lib/gcc/xtensa-esp32s3-elf/8.4.0/../../../../xtensa-esp32s3-elf/bin/ld.exe: C:\Users\Talha\AppData\Local\Arduino15\packages\esp32\hardware\esp32\2.0.14\libraries\BluetoothSerial\src/BluetoothSerial.cpp:715: undefined reference to `esp_spp_deinit'
collect2.exe: error: ld returned 1 exit status
exit status 1
Error compiling for board LilyGo T-Display-S3.