A helpful starting place would be to think about what, exactly, a dominant partner looks like to you. Does it mean someone who always takes charge? Someone who has a strong sense of their wants and boundaries? Something else? We sometimes think of terms like dominant and submissive as having very clear cut meanings that everyone agrees on, but actually those meanings can vary from person to person. Knowing what "dominant" means to you can help you figure out what traits you're looking for in a potential partner. Too, once you're old enough to use things like dating apps, there will be places you can go or platforms you can use that are designed to help people interested in dom/sub dynamics find potential partners.
Another thing to do would be to think about what other traits you want in a partner. Are there certain values or beliefs you hope to have in common with them? Is it important to you that a partner have a sense of humor, or be outgoing, or be reliable? Thinking about those other traits will help you identify people you'd want to date more easily.
You may already know this, but it would also be helpful to start managing your expectations around this sooner rather than later. Even someone who enjoys being dominant, or is pretty take charge in their daily life, is going to have days where they don't want to be the one making all the decisions, or days where they need support and comfort. Having that in mind will make it easier to remember that dominance is not the only part of a potential partners personality; it's one part of many that goes into the person you'd be building a relationship with.