BASIC PCB

Large truck control circuit used for vehicles carrying heavy objects

Coffee maker circuit uses PIC16F877A combined with esp8266

This is a simple green painted coffee machine test circuit

The car control circuit via Bluetooth uses a number of sensors and driver control

A practice circuit drawing combining Arduino nano and esp8266 with RFID and some other components

Door control circuit via wifi using esp8266

Below are some available PCBs, you can refer to it and learn the principles from it, it's quite basic and hope it will be useful to you.