Convert text frame to graphic frame

so I can adjust the size of the frame how I need and go to 'fitting' -  'fit content proportionally' so I don't lose any of the text when I downsize the frame.

How about just holding the Shift key and resizing with the Scale tool to resize frame and content at the same time, while maintaining the aspect ratio? Least amount of keys so far!

Select text frame (no text must be in it), context menu with  right mouse click  (or object menu) > Content > Graphic.

This is a workaround, but it should get the results you're looking for:

1) Copy the Text Frame in your original InDesign document containing the list with the Selection/Arrow tool. Make note of the height/width of the frame containing the text list when it's selected. Use the Edit>Copy menu command to copy the text frame with the list into the clipboard.

2) Create a new document through the File>New>Document... menu command. Make it just a bit larger -- .5in, 36pt, 3p0, 15mm or 1.5 cm wider and taller, depending on your unit of measure -- than the text frame you copied in the original document. Click the OK button.

3) Make sure your Selection/Arrow tool is still selected. Go to the Edit>Paste menu command and put the text frame with the list smack in the middle of the page of your new document. You should now see a new copy of the text frame just like the one containing your list in the original file.

4) Select the File>Adobe PDF Presets>[Press Quality]... menu command. This ensures you'll get the highest-quality version of your copied list. Name the export file TheList.pdf and save it to your desktop.

5) Go back to your original InDesign document with the list. Make sure your Selection/Arrow tool is still highlighted in the Toolbox panel, but that no element in the original file is selected. Choose the File/Place... menu command, navigate your way to the desktop and place your TheList.pdf file. You now have a graphic frame version of your old text frame, which you can size for frame and/or content size like any other InDesign graphic.

If this works for you, and I suspect it will work well, please mark this question as answered. That alerts the moderators to archive this post where it can help others who have similar issues as you've had. Good luck with your project.

Here is one method: Take the text frame of the long list, copy and paste into a new Indesign document. Modify as necessary, and save doc. Then back in the original document, place the new ID document. This placed ID doc will be treated like a graphic.