If you have knob and tube wiring in your house, you may not need to replace it before adding an EV charger!
When knob & tube was the go-to electrical wiring, homes required a main distribution panel where the knob & tube setup consisted of a large capacity wire that was "fed" into the home and broken down into "branch circuits." The original electrician working on your house would have likely installed a fuse-type panel, as the compact-style modern breaker was unavailable then.
Pictured below: Knob and tube wiring in an older home.
In our modern world, it's common practice to replace any older fuse panels with modern breakers, especially when a home is sold or remodeled.
With this replacement, all-new "branch circuits" are installed in the new panel with a modern style breaker at their distribution point. Even after replacement, the old knob & tube wiring still resides in the walls - coexisting with your home's upgraded main distribution system.