There is no time timer to limit the completion time in this sense. However, you can see how long each participant took to complete the questionnaire in the sample view. So there you can also view the results of participants who exceeded a certain response time and disqualify/delete them if necessary.
In the case of non-anonymous surveys, the response duration can be assigned to the individual participants; in the case of anonymous surveys, assignment is of course not possible. You can read here how to obtain a direct assignment of the results to the respective participant by name and what you should bear in mind when conducting non-anonymous surveys: Non-anonymous survey
You also have the option to set a fixed duration with start and end times for the survey. So, for example, if you want to conduct an online test that you want participants to solve within a given time, you can limit the duration to 1 hour, for example. Of course, this only makes sense if all participants can start the online test at the same time. We have summarized how to set the duration of the survey in a blog post: Set a fixed duration for a survey.
For more information on starting and stopping a survey, see our help desk: Starting and pausing a survey.
Feel free to use our free questionnaire templates for education as a guide when creating an online test.