How do to a Landing Page Test?

Hi y'all -- I need some advice and suggestions on doing landing page tests.

What is the best tool to do a landing page fake door test? We're trying to estimate demand for a new product and would like to run Google Ads to drive traffic and signup for a new service. Has anyone done this type of fake door test? What is the best landing page tool? Do you drive up signups for early access, or do you just measure the click-through as a gauge of interest in such a service?

Thanks,