Does entrance to the website by search and click on organic results expire the last session in google analytics with the same condition but another search term?
both organic search source (Not Ads) and before time based expiration of the first one. just different search terms.
A change in source will generate a new session (even during an active session), and according to the following page in the help docs, a user returning via the same source but different keyword/search term will also generate a new session
Each search term updates the campaign, so each keyword corresponds to a new session.