Since about 30 years I have worked with computers
, I have never heard things like that you are talking about.
In older days before the invention of the USB standard the computer have had a 9-pin or sometimes even a 25-pin serial connector which is connected to an UART chip on the motherboard. This we call here a real physical serial RS232
Later on the serial connection was dropped and replaced by USB (abbreviation for Universal Serial Bus). So most computers
have nowadays only USB connectors and even the Centronics printer connector (parallel port, 36-pins) was dropped.
So to connect a serial device to a modern computer you will need an USB/RS232 adapter which provides not a real physical com port but a virtual com port, usually in the range from com port number 4 and up. The com port numbers 1 to 3 are reserved to the real physical com ports and can't be used therefore. Responsible for creating the virtual com port is the USB driver of the USB/RS232 adapter. Any serial connection is limited to max. 115200 baud by the RS232
specs. And of course any created serial com port is seen in the device manager.
I hope this helps a little bit for understanding. For further and deeper information Wikipedia is a good source.