It is becoming more difficult to buy tracks from iTunes Store. There is a Today's Hits list which you can hear a sample of and buy if you wish, but there seems to be no way of searching for tracks of older performers as one used to be able to do. All links bring you to a page inviting one to sign up for Apple Music.
No problem here Lionel (running Music in Ventura). I just went to the Store front page & used the search bar. Results give you the option to select your library/Music/iTunes Store.
In the Ventura Music app the search field (where you type) is at top-left of the window. Cunningly placed at the top of the other side of the window is a 3-item selector to choose where you wish to search: make sure that's set to 'iTunes Store'. If it's set to Apple Music then you will probably get a subscription invite.
Lionel Ogden 