First, you must know and formalize your knowledge of ISO 9001:2015.
Second, you must know good auditing practices.
Third, you must have experience doing internal audits.
Fourth, you must have training to be a lead auditor.
Fifth, you should contact a certification body and ask how you can apply to become a Lead Auditor.
2.What suits me better taking the path of consulting or being an auditor?
Either path that you take does not invalidate the other. I believe it even enhances the ability of an auditor to have the experience of a consultant and vice versa. So, you can start as a consultant and internal auditor and then become also lead auditor for one or more certification bodies.