Searching for songs in iTunes store

The first thing is to make sure you are looking in the iTunes Store, not in the Apple Music streaming catalog, by clicking on the icon as shown below. For more details, follow the steps in here carefully:

Buy music from the iTunes Store - Apple Support

Good. BUT I want only song titles that contain a certain word. I do not want to see artists that have the same word in their name.

Example: I want songs with "Katy" in the title. I do not want to have to sort through all the Katy Perry songs and any other artist whose name is Katy.

Richard,

That is a reasonable request, but unfortunately it does not work that way. In the past, the iTunes Store had a "power search" that allowed keywords by field (as in your Katy example), but it was removed several years ago.