Pretty sure you need to be in a 145 environment..........
There are several categories of licenses which cover different levels and disciplines and a variety of routes exist to achieve them (This Blog Focuses on CAT A).
What is an EASA Part 66 CAT A Maintenance Engineers Licence
The Category A Licence: Ramp or Line Maintenance Certifying Mechanic typically performs relatively minor maintenance tasks and “simple” part replacements that may be required and to subsequently certify these tasks.
Cat A Aircraft Maintenance Engineers Licence (AMEL) allows the holder to issue certificates of release to service (When supported by an Approved Maintenance Organisation – AMO (145) following minor “Task Trained” scheduled line maintenance and simple defect rectification within the limits of the tasks specifically endorsed on the company authorization.
The privileges related to the certification shall be restricted to work that the license holder has personally performed (or is directly involved but requires assistance – for example wheel change) in a Part-145 organization.
https://sassofia.com/blog/all-about-easa-part-66-a-licenced-aircraft-engineer/