Startups rely on building an ensemble team that covers all the needed responsibilities with the minimum cost in staff. So the way those responsibilities get sliced depends on whose already involved.

If you're ready to explore smaller, earlier-stage teams, you can just pitch what you might contribute and see how well it fills a whole in the ensemble. Often, you'll be able to negotiate for a title that fits your own career trajectory, since titles are pretty much BS in that world.

Anecdotally:

I was once hired as CTO where the founding team consisted of high profile non-tech professionals who knew their industry and had connections to mine for sales/fundraising/partnership. And my own preference in that role is to not code as I find it hard to settle into the deep creative flow of my coding process amidst a lot of more piecemeal tasks and meetings.

I've also seen and passed on CTO opportunities where the founder was (say) a young MBA with some family wealth to seed the earliest days. That's often a more skeleton crew deal at that point, so the CTO may even be the only developer for a while.