Yes. You can resize a text layer, as you say, so long as you have not rasterized it. All you have to do is put the Text tool over top of the text, highlight it, and choose a new size.
You will need to apply Layer Style settings, if you do use text layers.
If you copy a text layer from one image to another or use an action to create a text layer and the new image has a different size, you will find that the text often appears screwed up (letters superimposed, etc.)
The technique I describe allows you to add a text layer once. Save it as a custom shape. Then, you can drop and drag it like any other custom shape. The last layer style will automatically be applied. Your text/logo/symbol becomes a preset you can use on any image. The size of the image will not matter.
This means you do not have to retype the same text layer over and over, rasterize it, apply layer style changes, etc. Adding a copyright, studio name, etc. as a watermark is quick and easy. As easy as using an action.
Cheers,
Mitch