Is it bad form to ask about secondary sales/liquidating some equity at my startup? I will not promote

I’ve heard about many startups allowing employees with vested equity to liquidate some % of their equity at some milestone say a Series C funding round. Is this one of those things that “just happens” in the sense that stakeholders just decide to allow this at some point? Is it something I should/shouldn’t ask about? I’ve been at my company for several years and we’ve been seeing tons of growth recently and I’d love it if I could liquidate even a small % of my holdings. I don’t foresee an exit any time soon