No, the due date is the initial condition for the escrow contract. Once the case is disputed (or before it), the buyer and seller must agree on a new deadline for service or product replacement in the contract chat.
There are no concrete requirements for a second due date because each case is different. The point of opening a dispute is to settle the disagreements between parties on mutual terms.
For example, the seller may have initially agreed on delivering the design for a website in 10 days (say August 26 is the due date) but did not take into account the fact that a buyer would send technical requirements a few days after. This leaves the designer less time to work with than initially agreed, and so, the design cannot be delivered by the due date.
In turn, the buyer opens a dispute to settle the new terms for the design. For example, the wireframe layouts must be ready by August 30, and the finished web pages – by September 3. This gives the designer an additional 8 days to fulfill the contract and deliver the product.
You can find more use cases for dispute settlements here.