Engineering Explained goes into some details about how CVT Transmissions work. Love them or hate them it is an interesting piece of tech.

“A continuously variable transmission (CVT) (also known as a single-speed transmission, stepless transmission, pulley transmission, or, in case of motorcycles, a twist-and-go) is an automatic transmission that can change seamlessly through a continuous range of effective Gear Ratios. This contrasts with other mechanical transmissions that offer a fixed number of gear ratios. The flexibility of a CVT allows the input shaft to maintain a constant angular velocity.”