Align text content left and right within the same layer

Yes, you can. Just select the target paragraph, then change the alignment or other properties.

But this is not a proper way to maintain your document, since it's very easy to mistakenly apply the text style to the whole text layer.

Unfortunately, no. Everything in the Alignment, Opacity, and Blending sections of the inspector apply to the entire text layer. The rest apply at a character level.