Yes and no... It would be fairly easy to count the characters in the plugin but with BBCode you could have 1000 characters in the signature but it only displays a short 100 of them as actual text.
You could filter out the BBCode but it is more difficult.
Worse is that in my experience it's images which take up a lot of room, not so much text, and there is no way to check the size of the image each time it is loaded.
There was a thread somewhere here on a mod or template edit that allowed for a max signature height in pixels, and anything longer than that it would show a scrollbar so it didn't take up the whole page.
Here is the link actually:
https://vborg.vbsupport.ru/showthrea...68#post2085268