Yes! You can create an extension after an assignment due date has passed, and, in most cases, do the same for assessments (quizzes and tests).
If your student hasn't yet started their assessment, or if they have remaining attempts, you can give them an extension.
If a student has already completed all their attempts on their assessment and you want to let them retake, you can reset the assessment to let them back into the assessment. Either reset only their last attempt to give them one more try, or repeat the reset process to allow them multiple retakes.
For more information on resetting assessments, check out this article.