Sometimes your cable's just aren't long enough. However, you can purchase extension cables.
Key requirements for an extension cable
For pen tablets
It needs to support data and small amount of power - any USB 2.0 extension cable should work
For pen displays
It must support data
It must support DP alt mode
it must support the resolution and refresh rate you need
it must support sending enough power to your pen display
SAFETY CRITICAL it must support AT LEAST as much power as the tablet's original cable. If it is not rated to handle that much power it will be a safety / fire risk.
To better understand the needs of connecting a pen display see: Connecting a pen display.
I use a 2 foot UseBean USB-C Extension cable. This product has worked well for me. I have run up to 4K@60Hz using this extension cable.
I used it in these ways:
With a Huion Kamvas 22 Plus: I connect it to the USB-C end of a Huion 3-in-1 cable.
With Wacom Cintiq Pro 16 (DTH-167): I connect it to the the USB-C cable that came with the Cintiq.
https://www.amazon.com/dp/B0BB13ZNPQ
The specific USB-C extender above has a USB-port that fits into some pen displays, but some other pen displays have their USB-C port deeper inside and this cable cannot fit into those areas.
For example, this extender does NOT go deep enough to fit into a Huion Kamvas 13.
Teoh on Tech: Using Extension Cables with Pen Displays or Graphics Tablets (https://www.youtube.com/watch?v=y7kvIGbnjzo)