Can I use iPad without Wi-Fi?

Yes.

Instead of using a WiFi or Cellular connection, your iPad can access the internet via a wired ethernet connection that itself has an internet connection. To do so you’ll require an ethernet adapter suitable for your model of iPad.

Assuming that your iPad Pro has a USB-C port, you might consider something like this…:

https://www.ugreen.com/products/usb-c-to-gigabit-rj45-ethernet-adapter

Alternatively, there are compatible USB-C hubs that incorporate a standard ethernet interface - such as Anker:

https://www.anker.com/products/a8338

I suppose that depends on what you want to do with it. Many of the native apps will work without an internet connection. Some won’t. Most 3rd party apps won’t.

In order to access the Internet and the ability to access third party apps and other Internet-based features of your iPad, to use with that expensive iPad model, you either need to use a Home wirleles, Wifi network setup, have easy access to free WiFi locations or, if you own a cellular service smart phone, use the smart phone's own built-in WiFi hotspot feature with your iPad or a using a cellular service using a dedicated, portable, mobile MFi ( WiFi ) hotspot device witn your iPad.

You will need some wireless means to get onto the Internet, send/receive email, use video caling services and anything else that needs/requires access to the Internet.

Best of Luck to You!