That's not how the policy works anymore.

You can't just roll up to border. There's an app used to file claims before departing, and if you just show up at port of entry without an appointment for your claim, or you are caught crossing the border illegally you get expelled back to Mexico, with some exceptions for unaccompanied minors, etc.

https://www.nytimes.com/2023/01/05/us/politics/biden-border-crossings.html