Use the cover letter to explain the transition only if it helps the recruiter understand why the move makes sense. You do not need to restate the fact that you worked in engineering.

The resume shows what you did. The cover letter can add the logic connecting that experience to consulting, especially when the move might otherwise look abrupt.

Instead of saying, 'I am an engineer seeking consulting,' you could briefly explain that leading cross-functional decisions made you realize you want broader business problem solving and client-facing work.

Give the transition one concise explanation, then spend the rest of the letter on firm-specific motivation and the strongest evidence that your background transfers to consulting. If useful, this guide on consulting resume gives more detail.

Cover letter is where the 'why this switch' logic can actually help.