Huge type cursor in photohop CC2018

That often indicates an unintended change of units.  For instance if you changed the image size with resample turned off, and type is set to a linear unit, then despite the image still having the same pixel size, its linear, and hence type size, will be different.

The text below was done on a 1000 pixel high document, and the only thing that changed was the resolution.  You can see the same 30pt text is wildly different. — if you were to measure it, the ratio would be exactly 72/300ths

There other ways this sort of thing can get you, but I suspect this will put you on the right track.  Another regular one is where you have been working in pixels, and make a new image without realizing you are now using inches.  You make your new document 1000 x 1000 @ 300dpi, and suddenly type layers are barely visible because the image is actually 300,000 pixels square, and a 50px type layer is going to be a tiny dot on the screen.  We see this a couple of times a year probably.

Post a screen capture in the tool option bar what font and font sizes is set? How big are the characters what zoom percent are you at. If all setting look good reset all tools if that doe not solve you problem reset your Photoshop preferences.