Right now it appears to be impossible to have a view that says, "show me everything with a start date older than 30 days" because the 30 days gets turned into a fixed date. Or, "Show me tasks starting in the next 7 days."
That means views have to be manually updated every day or week.
Kevin Pearce asked for this here (https://feedback.clickup.com/feature-requests/p/due-date-filter-always-based-upon-todays-date-ie-next-7-days) and the request was closed for no support - but I can't imagine this isn't needed by many people.