You can opt to use the Time field between the 12-hour or 24-hour time format. If you want to change the format, select the field in the Form Editor and go to the Edit Field panel on the left. Afterward, use the Time format dropdown and select your desired time display. If you select the 12-hour format, form visitors can choose between AM and PM by using the clock icon inside the field.
You can also set a default time on your online form. The default value now can be used for both the 12-hour or 24-hour formats. This will automatically fill in the current time when the form is opened and filled out by the form visitor.