Some iPads have a standard 3.5mm headphone jack socket but some don't. See here:
https://www.businessinsider.com/does-ipad-have-headphone-jack
If your iPad does have a 3.5mm headphone jack socket you can use any speakers (or, say, a hifi system) that can accept an input via a 3.5mm jack plug, such as this one:
https://tinyurl.com/yby92m6d
However it would probably be simpler to make the connection over Bluetooth, removing the need for wires and allowing you to position the speaker further away from your iPad. There are vast numbers of suitable speakers available, from not much more than a tenner (both online and in discount stores, such as B&M) up to many hundreds of pounds. Here's just one example:
Amazon.com User Recommendation