You can set the field to be as large as the largest you would want it, then set the sliding options to allow everything below it to slide up depending on its size.
I don't think there is a way in Filemaker to have the field enlarge from what you define in the layout.
In FileMaker, fields can shrink but not expand in regards to the amount of data in the field. There are anchors that can resize a field, but they are in response to changes to the window's size.
As Mark has already stated, you can choose a large size for you field and set it to slide/resize. This works for printing, previewing and saving as PDF, but not for browsing. Thus, you often need two layouts in this situation. One optimized with sliding options for printing and the other with a scroll bar on the field for data entry and browsing.
Key facts about sliding layout objects:
- It's only visible in preview mode and when you print/save as PDF...
- All layout objects below and in the same layout part as the slide/resize field need to also be set to slide up and resize.
- Objects in headers and footers will not slide.
- Portals will shrink/slide to fit the number of rows of records, but fields within the portal row will not shrink/slide.
- Consistent side borders are difficult to achieve with sliding fields.