Don't ever assume you're not the right fit for a gig! If your agent sent the audition to you, they have confidence in your ability to book it. Recently, I booked an explainer video gig where my first thought after receiving the audition was, "Oh man; I'm not the right fit for this." I was wrong! We should never limit our abilities in this business.
A former student of ours thought he could never do animation. His niche was medical narration. Now and then, his agent would send him an animation audition but he always turned them away. So he finally did one for the fun of it and guess what? He went on to do animation work in L.A. In voiceover, there is always a surprise waiting to happen. A talent tucked away inside you somewhere.
When I started my career, I thought commercial and corporate narration would be my two niches! In the last six years, I have recorded several theme park announcements for various amusement parks and events around the country. I never saw this niche coming! A client had found my website and wanted me to do a few reads for Stone Mountain Park in Atlanta. I booked the gig but the best thing about working with this client is that he handled the creative for about a dozen different parks and events around the country, so I've had the honor of providing theme park promos for a variety of different locations.
So step outside of your comfort zone once in a while. Be open to a variety of different projects, even if you don't always think you're the right voice actor for the gig.