Where/how can I connect my earphones to my new IPad?

If your iPad has a Lightning connector, you can connect standard “wired” headphones with a 3.5mm plug by using Lightning to 3.5mm Headphone Jack Adapter:

https://store.apple.com/uk/xc/product/MMX62ZM/A

If instead your iPad has a USB-C connector, you can use a USB-C to 3.5mm Headphone Jack Adapter:

https://store.apple.com/uk/xc/product/MU7E2ZM/A

Alternative to wired headphones, consider using bluetooth wireless headphones/earbuds - such as Apple AirPods, AirPods Pro or AirPods Max - or third-party equivalents:

Airpods - Apple

Not all iPads have audio socket.

Use bluetooth headphones.

Depending on which “new” iPad you purchased, there are two choices of audio adapters to purchase to use wired earphones/headphones.

Lightning to 3.5 mm Headphone Jack Adapter - Apple

OR

https://www.apple.com/shop/product/MU7E2AM/A/usb-c-to-35-mm-headphone-jack-adapter

Otherwise, the ONLY other option is wireless, Bluetooth earphones/headphones to use with your new iPad model.

Best of Luck to You!