FileMaker fields can shrink but they can't grow. You can set up your print layout with this field sized to be very large. Then use the Inspector to set the field to slide up/ resize enclosing part. Any layout objects in the body that are below this field should also be set to slide and shrink.
The sliding will only be visible when you preview, print or "save as PDF" the layout.
There is another option. Since this is a "list of records", put these entries in a related table and design your layout to print from a layout based on the related table. The main info from the parent table can be included in either the header or possibly a sub summary part. The invoices starter solution uses this method to print invoices so you can examine the layout and scripts of this starter solution for clues on how to use this, more flexible approach.