The ideal UX process doesn't exist, there are as many different possibilities as there are organisations and people building or improving websites and apps.
Depending on the type of your project, your organisation, what you already have or not, you can choose one or another method, start from the very beginning or jump in the middle of it.
This is an overview of what is above the pure UX stack and process (Company vision to customer experience) and is summarised in the UX layers graph as the business goals.
After that you are finding back the several other layers purely related to user experience.
These are the big steps and phases on which you are
Design thinking in UX
Lean UX
Agile
