I use an ancient copy of MS Publisher that does everything I want. For going a bit special, it has a feature called "WordArt" that lets you curve a word. I believe that the feature is in MS Office (don't know, haven't got it). There is something similar in Libre Office in the "Draw" part called "Fontwork". I found this a lot clunky to use, and, already having the best tool, have never bothered climbing the learning curve.
For simple text, any word processor will do the job if it can access and use the fonts, even Notepad.
Decal printing is simple if black lettering is what is wanted - it gets a bit complex when colours are involved because a white background is needed if the print is not to just vanish.