In terms of walk-in, there's "urgent care" and similar things. And of course the emergency room if the need is severe. Telehealth was vastly expanded during the pandemic and has stuck around to a significant degree.

Just checking my doctor's group, they have multiple appointments available for new or existing patients in all 7 of their locations around Austin as early as Tuesday - and that's probably only because Monday is a holiday. The only caveat is that you have to accept whichever doctor is available, rather than selecting you PCP.

I know it's a big country with a lot of variability of experience, but this has been the case everywhere I've lived.