iOS 13 supports a mouse, but there are other ways to use these features. YouTuber Napabar connected the keyboard and mouse used on a Macintosh computer 35 years ago to the iPhone X.
Another way is needed to connect the M0110 keyboard and M0100 mouse for the Macintosh, which appeared 35 years ago, to the iPhone’s Lightning port. Plug the USB conversion adapter into the M0110’s RJ11 cable and the M0100’s DE-9 serial port connector, and connect the iPhone Lightning cable to the USB hub. This way, you can use the keyboard and mouse at the same time. For reference, to use the mouse in iOS13, you need to set the accessibility (Assistive Touch). Related information can be found here.