In the library object, select a frame that can be resized for the text fitting purposes, and then in Fitting, enter the value of the allowed number of lines to be applied.
The value consists of four numbers, e.g.
2,1,0,0
•The 1st value is the variation of the top edge - how many vertical nudges (VGs) it may go up;
•The 2nd value is the variation of the top edge - how many VGs it may go down;
•The 3rd value is the variation of the bottom edge - how many VGs it may go up;
•The 4th value is the variation of the bottom edge - how many VGs it may go down.
Examples
•Allow the frame to become longer for 3 VG if needed
0,0,0,3
•Allow the frame to become longer for 3 VG and shorter for 2 VG if needed
0,0,2,3
•Allow the frame to become longer for 3 VG extending down, or for 1 VG extending up, if needed
1,0,0,3
•Allow the frame to become longer for 3 VG extending down, or shorter for 2 VG moving top down
0,2,0,3