No. Behind the wheel driving tests are done only by appointment at any DMV, not just San Mateo. There is a significant wait time but if you can afford to travel further, try booking an appointment in Oakland or somewhere further out and you'll get an earlier date. Alternatively, you could call them up periodically and check if anyone cancelled and if they could accommodate you instead. All the best!
I don't think you can do a walk in for behind the wheel test. Call or check their faq's https://www.dmv.ca.gov/portal/dmv/detail/online/appt/apptfaq
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