I think if you mean pure Zoom webinar no.
According to the following Zoom support document;
https://support.zoom.us/hc/en-us/articles/211579443-Scheduling-and-customizing-a-meeting-with-regist...
It appears that you can only close registration after the event ends.
Close registration after meeting date: Select this option if you want to prevent anyone from registering after the meeting date and projected end time. Participants can still register on the event date and once the meeting starts, as long as it is before the projected end time of the meeting. For example, if you schedule a meeting for 9 AM with a duration of 2 hours, the registration will close at 11 AM.
Perhaps using the manual approval process would allow you to deny entry to late arrivals?
https://support.zoom.us/hc/en-us/articles/360054446052-Managing-meeting-and-webinar-registration
If you have a Zoom Events licence or perhaps Zoom Sessions licence then it may be possible through the extra functionality those tools provide.
Regards