appointment

You can purchase directly over the phone.

Call Customer Support (800) MY–APPLE (800–692–7753)

I can add—In the USA "stock" items ship next-day express shipped from local warehouses, "built to order" (BTO) come from China—and there may be some associated delays

If you want an instore you do not need an appointment to purchase.

due to the temporary closure of Apple Stores and the staggered reopening there may be some delays.

ref: https://www.apple.com/shop/browse/store/temporary_closures )

call you local store if you need more information here.