Control your LED on Arduino UNO using Blynk App.
Use the Blynk app to control the RGB LED, the onboard LED, and the LED expansion from your phone.
Control an external LED light from anywhere in the world using the ESP8266. The GPIO pin serves as an output source to the LED.
The simplest project in Arduino that one could learn is to control the on-board LED via Blynk app.
I made LED EyeBall controlled by Blynk using Adafruit Feather 32u4 Bluefruit LE. I can easily using Blynk!!
If you want a NodeMCU device that could help you to control all your house electrical devices, then this will be your best guide
Control an on-board LED.