I assume you seek to include a large table in print thesis and you live in a country with access to paper in either one of ISO A series (if unfamiliar to this definition, see here) and you already know which data really need to stay (ask a colleague, your supervisor).
Do not shrink the font size to add more content on an already jammed page, but consider to print the large table on a sheet of ISO A3 (landscape orientation), fold it, and bind this into the rest of your thesis print on ISO A4 (portrait orientation). This is much easier (than with standard US paper formats)* because within the ISO A series, the long side of a smaller paper format is as long as the short side of the next larger paper format.
You do not need to fill all the A3 page in the horizontal direction. It actually is better to use the same font size on the lager page as in the other part of your thesis. For the potential trim to a smaller size of «the table page» (then neither ISO A3, nor ISO A4) and folding, reach out for help by the staff members of a good printer's shop, who will bind it with all the other pages into your thesis for you.
It equally is a technique you find for business reports comparing selected key figures of debit and credit about the year to be reported side-by-side with the numbers about year before the one of principal interest. On occasion, architects, engineers, etc. use it to include their plans and drawings. For illustration, see for example this or even this video.
*) It is not an insurmountable obstacle for a good printer's shop.