Hi, if you are able to use Image-Line FL Studio, try using Newtone plugin that comes with it (not sure, though, if it comes with all versions or only with Producer edition and above). It gets the job done, doing some minor enhancements can be done there pretty easily. Not gonna lie, I've used it when doing my cover, because I was so nervous when recording it and my voice was very shaky... If only that shaking was a sign of the natural vibrato finally making its way to my voice. Spoiler: it wasn't
However, if you already have the Steinberg Cubase, you probably won't want/need to use another DAW for pitch perfecting those vocals. In that case, the plugin called Melodyne should do you the best. From what I've read it is more convenient, but I haven't tried it myself, so I can't tell you my opinion on it... All I can tell from screenshots is that its user interface looks similar to Newtone's, so it should be really simple to use.
Hope this helped... If not, well, at least I've tried