Every tour renders at 1080p, on every plan. There is no lower-quality tier and no upgrade that makes the video sharper.
That is full HD and the right size for the MLS, for social, and for sending to a client directly. Instagram, Facebook, TikTok, and YouTube all re-encode on upload, so a larger file would not survive the trip.
Your source photos matter more than the export setting. A tour built from small or soft photos will look soft no matter what it is rendered at, which is what the Image Studio upscale is for.