Make a default date range a global setting, instead of a per-search setting.
New searches will default to this global setting (and the user can then decide to expand the search to different date ranges only if desired).
99% of the stuff on the web is outdated. I really don't care about news or articles from 3+ years ago in most of my searches. Most likely, even the entire technology platform they revolve around has changed, so the information just poisons my search results with data rot.
Much like setting up their lenses or other search features, they would also go to the settings to set a default date range that is then being honored for all future searches. (unless lens or other settings override these defaults).
Users would to this feature via the search tab in settings. and it would be a similar input control as the one on the kagi search home page for "Time"