If you pay for (not a trial), you can pause it. Go to your Corel account > Subscriptions > Select "Suspend." This stops the billing clock. Corel allows up to 90 days of suspension per year. This does not work for the free trial.
While there are no official "extension" buttons, you can maximize your time or transition to a paid plan effectively. Official Ways to Continue Using CorelDRAW how to extend coreldraw trial
Corel tracks your trial via machine ID and email. This gives you a new 15-day trial on a different computer. If you pay for (not a trial), you can pause it