No, it is not possible to prevent a ticket from changing to a Closed status after spending 28 days in a Solved status. This is a system rule that can not be adjusted or altered through the use of automations and triggers.
As the rule for closing tickets after 28 days only applies to tickets in a Solved status, a workaround to prevent tickets from closing is to utilize the On-hold status. The On-hold status allows users to keep tickets beyond 28 days, without keeping them in an Open or Pending status. Tickets with the On-hold status are not affected by the system close rule and are allowed to remain in this status indefinitely.