Are you a Stryd user? I ask because Stryd has a race power prediction feature that is highly reliable. Effective race pacing is done mainly by feel, but this feature will give you a good initial target. Use it to regulate your effort for the first 1K or so, then assess how you’re feeling and adjust based on your sense of the sustainability of your pace for the remaining distance. And yes, the objective is to cover the full distance as fast as you possibly can, but to do so, you can’t be running as hard as you possibly can until you’re within sight of the finish line. Here’s some additional guidance:
How to Set a Good Race Time Goal