Code for ESP32 DS18B20 with I2C LCD.

ESP32-DS18B20-I2C-LCD.ino

#include <OneWire.h>
#include <DallasTemperature.h>
#include <Wire.h> 
#include <LiquidCrystal_I2C.h>

#define DS18B20PIN 16

/* Create an instance of OneWire */
OneWire oneWire(DS18B20PIN);

DallasTemperature sensor(&oneWire);

LiquidCrystal_I2C lcd(0x3F, 16, 2);

byte degree_symbol[8] = 
              {
                0b00111,
                0b00101,
                0b00111,
                0b00000,
                0b00000,
                0b00000,
                0b00000,
                0b00000
              };

void setup()
{
  /* Start the DS18B20 Sensor */
  sensor.begin();
  lcd.init();
  lcd.backlight();
  lcd.createChar(0, degree_symbol);
  lcd.setCursor(0,0);
  lcd.print(" DS18B20  with ");
  lcd.setCursor(0,1);
  lcd.print("  ESP32 DevKit ");
  delay(2000);
  lcd.clear();
}

void loop()
{
  sensor.requestTemperatures(); 
  float tempinC = sensor.getTempCByIndex(0);
  lcd.setCursor(0,0);
  lcd.print("Temp = ");
  lcd.print(tempinC);
  lcd.write(0);
  lcd.print("C");
  delay(1000);
}