Two to five metres
A longer USB-C cable is a different engineering problem.
There is no useful universal “maximum USB-C length”. The practical answer depends on power, data rate, cable construction and the exact devices at both ends.
Voltage drop and heat matter
Longer copper adds resistance. A charging cable must keep voltage drop and temperature within the applicable limits at its stated power. Cable gauge, connector quality and electronic marking matter more than the connector shape.
Higher bandwidth tightens the channel
Signal loss and timing margins become harder as passive copper gets longer and data rate rises. USB-IF describes cable lengths in its specification as informative practical lengths based on cable performance requirements—not a blanket permission for every combination.
Electronics can extend reach
An active copper cable includes electronics in the data path. That can support a longer run, but may introduce direction, power or compatibility limits. Those limits need to be stated for the exact model.
Optical solves one problem, not all of them
Optical construction can carry high-bandwidth signals across a room, but power capability, direction, durability and device interoperability still need separate evidence. It should not be marketed as a normal passive cable made longer.
Use one purpose-built assembly
usb-c.store will not sell the common USB-C male-to-female extension format. For reach, choose a single cable assembly designed and tested for the full run and required capability.