The max-lines property limits the content of a block to a maximum number of lines before being cut off and can create a line clamping effect when combined with block-overflow. In fact, both properties make up the line-clamp property, which is a shorthand for combining them.
The block-overflow property truncates text and indicates more content follows by inserting an ellipsis or custom string after a number of lines that is set by the max-lines property.
The line-clamp property truncates text at a specific number of lines.
The spec for it is currently an Editor's Draft, so that means nothing here is set in stone because it's a work in progress. That said, it's defined as a shorthand for max-lines and block-overflow, the former of which is noted as at risk of being dropped in the Candidate Recommendation.
You want X lines of text. Anything after that, gracefully cut off. That's "line clamping" and it is a perfectly legit desire. When you can count on text being a certain number of lines, you can create stronger and more reliable grids from the elements that contain that text, as well as achieve some symmetric aesthetic harmony.
There are a couple of ways to get it done, none of them spectacular.