How to get response of issued AT command for ES266 on Arduino programatically?

I'm successfully running AT commands via the Serial Monitor. But now I'm issuing AT commands via Arduino code and facing problems getting the correct response.

Goal: After issuing AT commands programatically, knowing whether these run successfully or not.

Microcontroller: Arduino Uno

#include<string.h>
#include<SoftwareSerial.h>

#define OK "OK"
#define SERVER_PORT 1234
#define RX_PIN 2
#define TX_PIN 3

SoftwareSerial ESP(RX_PIN, TX_PIN);

void setup() {
  Serial.begin(115200);
  Serial.println("First serial");
  while(!Serial);
  ESP.begin(115200);
  Serial.println("Second serial");
  while(!ESP);
  //Enabling multiple connections
  ESP.println("AT+CIPMUX=1\r\n");
  while (!ESP.available());
  String muxResponse = ESP.readString();
  Serial.print("muxR:");
  Serial.println(muxResponse);
}

void loop() {
  if (ESP.available()) {
    String val = ESP.readString();
    Serial.println(val);
  }
}

After running the above code I get the response in the Serial Monitor like:

muxR:AT+CIPMUX=1


busy p../

OK

I'm getting special characters too.