Look for force-multiplying effects you've contributed to. That is, focus on the things that you've done that have increased the effectiveness of both your immediate team and the larger product organization.

Demonstrate that you're already excelling at the responsibilities of a Sr. Engineer: You're taking ownership of new projects and crushing it. You're mentoring other engineers. You're making effective product decisions based on dynamic business constraints. Cite examples.

Point to some projects and explain your contributions in terms of customer value. I find that explaining the problems you're solving through a business lens is an effective way to signal that you can quickly grasp new business challenges and run with them. Employers are looking for people they can trust from Day 1.

Hope this helps :)