Services where you can order silicone molding (USA, China)?

Question

3D printers

I am a complete newbie to this process and have a hard time imagining it. I'm making a PoC of one thing and it became necessary to make a simple silicone part (16x16x1 cm). 3D model, CAD files I can do.
A quick googling was unsuccessful.
Can you tell me if there are such services?
It is also possible to print something like this on a 3D printer, but then the question is - the plastic should be quite flexible and cold-resistant (the thing will actively bend and unbend on the street, including at sub-zero temperatures)
It would be nice if you shared links where to start study of the issue - preferably US services, maybe territorially I am in the USA