Limit the excerpt length for all portofolio items

Hello

We are using portofolio items to show those in the Masonry view side by side.
Please see the attached image. As you can see, box #2 (right) is higher then box #1 (left).
The client wants to use same width + height for all images, no cropping allowed.
Please do note, that all of the images we use has the exact same size and aspect ratio.

Is there any function that we can add to our theme’s child functions.php file that will simply limit the excerpt for all of the portofolio entries?
Basically if the text is 50 lettes and we need only 30, then the text is get cut after 30 letters and the “…” is added at the end.

Please assist, thanks (we’ve tried nearly all possible solution from this forum with no success).

All the best