It totally depends on what the manufacturer has listed the wire-nuts for. The manufacturer tells Underwriter's Labs which several dozen size combinations they'd like their twist-connector tested for... and then UL torture-tests each of those combinations, resulting in a UL listing.
And somewhere on the web is a super-boring spreadsheet of each and every single one of the combinations for which that twist-connector is listed.
Those docs can be a bit hard to find on the web, they love to steer you toward the color brochure which armwaves something like
2x#16 to 3x#10 - which doesn't tell you a darned thing. An email to your vendor's support department ought to get you the link.
For instance, Ideal chooses to not list their "red" wire nuts for 6x14AWG. No idea why not. Somebody does. If it's not listed, you can't use it - the end.