Yes it is true. The first and to a lesser extent, the second album usually has the characteristic sounds of that artist in which they put a lot of effort and originality in. They really want to make it "theirs" to build up a fanbase. Then let's say 4 months pass, they earn money and now live a more lavish lifestyle. But uh oh the coffers are going kaput. So now it's time to make the next album but they just want to sell records to maintain their luxury lifestyle and fame, rather than entice a fanbase. So they are just like yeah whatever, I have annoying teen brats who will buy my album even if I squeal like a whale in the microphone for 45 minutes, because I am a brand. Artists are more "desperate" and hardworking at the beginning. Ofc this paradigm does not always apply. I am aware that Taylor Swift started off doing country things. But then she turned pop to amp up the record sales and for maximum fame and money. The Beatles on the other hand were at their prime creative spark in the 60s but starting from 70s they kind of went downhill from there. Well ofc music is subjective but I am just basing this on the chart position and sales which may suggest how good the song is (even that is up for debate).