Force Sidecar to use usb connection macOS Catalina has a feature where you can use your iPad as a secondary display for your Mac. I have a Macbook Pro 2016 and a 10.5 inch iPad Pro 2017. Both are officially supported for the latest versions of macOS and iPadOS and support Sidecar.

I installed the latest version of iPadOS and macOS and tried using Sidecar and it kinda works but it's extremely laggy and blurry and almost unusable and if I turn wifi off in my mac it disconnects and complains about wifi being turned off.

As far as I know this feature can work with wired connections as well and I tried connecting iPad to Macbook using a (Lightning -> USB A) to USB C adapter and also also tried using a USB 3 hub connected directly to the laptop using USB C and it still does not work.

Is there any way I could force Sidecar to work over a wired connection?
I struggled with the same problem and just now finally solved it. The issue was for me that I didn't earlier "Trusted my iPad" on my mac, and "Trusted my Mac" on my iPad.
Here's a how to: 
https://support.apple.com/en-us/HT202778

After doing this, it finally connects via cable and is hopyfully less buggy. x'3