IDEA 2004 defines this, and quite clearly:
LEA is one of those special education acronyms parents need to learn. Many times when you start an IEP meeting, a staff person will say “And I’m the LEA today.” That means that that person is designated to represent the district. They get the final say at the meeting as far as what the district is going to agree to. So, when you RSVP to a meeting, you want to make sure that there is a good LEA there.
Short answer, no. They are not mandated IEP team members. However, OSEP has provided an OSEP guidance letter on this.