You can track visitors using a form, without converting them into People profiles immediately.
Create a form and make sure you use Profile Fields (not general fields), especially:
Name + Email or Mobile Number. Make these fields mandatory, regardless of any other information you might want to add.
Share the form using a QR code or shareable link.
All form entries will be saved under Forms > Submissions.
Later, if you want to convert selected submissions into People profiles, you can do this by going to Submissions > Select submissions > Bulk Actions > Add People. Learn more.
This way, visitors are not counted in your People limit unless you choose to add them as People profiles.