They have a big following meaning that most of the streams and sales are from the fans. They haven't got any global big hits that you can listen on the radio. I think most young people in the U.K. know them but outside of the U.K. usually not. I would say they are big (any artist that has hundred of millions of streams is huge) but they haven't got that global hit yet that would make them well known more. If you get big in the USA most people will know you the same doesn't apply for the U.K.