So, I'm going to assume your stove is running at high pressure (regulatated down from the tank pressure to about 16psi) this is what I tihnk most of these outdoor camp stoves with the rigid regulator do. This is different than some of the grills that run on low pressure, about 0.4psi, same as RV propane plumbing. If your stove is low pressure then you have lots of options for adapters. Look at companies like Torjik https://torjik.com/ and you can basically just make whatever tubing and stuff you want with parts from Amazon and other distributors.
If your stove is more likely high pressure then Camp-Chef/Stansport (same manufacturer) has what I think you want:
https://www.campchef.com/mountain-series-flexible-regulator-kit.html
https://www.amazon.com/Stansport-30-Inch-Regular-Appliance-Cylinder/dp/B005EUE214
However, I'm not completely certain if they use the same connector... based on the Q&A on Amazon it looks like the fitting is different
I think Camp-Chef/Stansport uses M14-1 threads but I don't heave a measurement for the length of the male threaded portion on the stove.
Check if coleman has the accessory you want.
Alternatively, consider getting a 5lb propane tank if you can find an adapter for this.
I did find this one... someone posted in the answers section that they think it'll work... https://www.amazon.com/gp/product/B00M2UDPAI/ref=ask_ql_qh_dp_hza
Not really sure though, there seem to be a lot of these that are kinda sorta similar, and it doesn't give a compatibility chart anywhere in the part description... >_>
EDIT: He replied with a picture of the part! And it looked identical to the one I've got! so I tried it again. With a lot of extra force, it looks like the one I have fits fine... so maybe it was the right one all along? Maybe its just a seized up rubber gasket that's a little too big, preventing me from pushing it on all the way easily? I wonder if I can find that little red knob anywhere now... >_>