Keyboard trays are becoming very rare, I have no idea why. They are ergonomic and use desk space much better. I never found a desk that comes with one, I just bought one and added to my desk. I bought one like this

https://www.amazon.com/Dofover-Keyboard-Drawer-Extension-Adjustable/dp/B0755DBC5X

It was pretty cheap, I already had a wooden board in my house to use as the tray, so I just cut it to size, installed the rail track and installed it in my desk. It even has a height adjustment.