By means of a relay, a circuit with much more power can be switched with a relatively small current.
Customer reviews about Relay modules
W. Gracht5V Relay module 8 channelsWorks well, with 8 channels there are quite a few options to control devices. The optocouplers keep the signal safely isolated.
Tim GTimer relay module - 12VI had a little trouble setting the correct mode, but once you get the hang of how the buttons work, it's pretty easy to operate.
Anonymous5V Relay module 2 channelsProduct is exactly as described and works well. Perhaps a small manual could have been included about the inputs (low active) and the jumper for separate power supply.