I have a pos billing system and I want to modify some things and add more modules (Codeigniter web PHP, with a MySQL database)

I have a pos billing system in Codeigniter web PHP, with a MySQL database with 62 tables I want to modify some things and add more modules modification list * modify invoice format in total the ticket as PDF * In the add product window, it is necessary to have a sub family family and some other details * connect the system to the website that I have so that when I want to sell an item in the virtual store I click on a button and it sends to wordpress * multi currencies that I can charge in dollar and colon at the same time and check the open box button and some other little things so that the system works well and a cell phone app * complete marketing model for whatsapp facebook email with the same phone number as the whatsapp function to users at the same time * put the system as REP so that it works offline as online * work in excel the following (add purchase) and others * mod focus something on purchases - add transfer -