How to Call Custom Methods In Odoo Using XML-RPC

i want to learn owl tempalting in odoo can you make playlist on it how to create odoo templates and make our own module from scratch using js and python backend

can you tell in which cases we can use this library is it fast to use xmlrpc or we can build website on react and get data from odoo using xmlrpc or we should create website inside odoo what do you think ?