This is mostly through powerscaling. Frieza's third and final forms are both Solar System level scaling from a calculation of a feat of First Form Frieza: https://www.narutoforums.org/threads/friezas-supernova-frieza-really-wasnt-kidding.1086728/. This would put him at at least Large Star level+, especially since the feat was extremely casual. Going by that, Frieza's third form should definitely be Solar System level. As for Multi-Universe level, it's because of Hit. Look at his profile and it explains why he's Universe level. Goku in the Future Trunks Saga is far stronger than he was when he fought Hit (so he should be at least Universe level+), and SSR Goku Black is far superior to even that. Later, Goku and Vegeta become powerful enough to completely dominate Goku Black and put up a fight against Fusion Zamasu. In the Universe Survival Saga, they are even more powerful than they were before. That's why a lot of the high tier DBS characters are Multi-Universe level.
I don’t think Hit made an entire dimension I think that can relate to the same mistake people made about Vegeta destroying the Hyperbolic time chamber, which is only a planet level feat. That’s like saying Obito is multi universe level because he controls the kamui dimension.
@M+S=Greatness: Not entirely. The Hyperbolic Time Chamber actually has an even more reliable statement saying it's a universe rather than a planet. Also, it's stated Hit creates a parallel world, parallel being the most important key word, since that would imply it's around the same size as the actual world. Also, Goku's 2-C since he's become stronger than when he accomplished Low 2-C feats, not because he accomplished Low 2-C feats and we put him as 2-C for that. Big difference.
actually, the dragon ball universe = one multiverse. it has countless realms, dimensions, imprison realms, heaven, hell, kaioshin realm, etc. in fact there are 10 dimensions in a single universe if i lowball it too much.
@M+S=Greatness: You're not getting it. The word "parallel" implies Hit's world was as big as the universe itself, AND Vados said he "utilizes time to create a space." That sounds exactly like a space-time. Not to mention that the Hyperbolic Time Chamber is called a universe and Vegeta destroyed it, and that Black forced an entire space-time continuum to serve him. There are SEVERAL Low 2-C feats in here, and Soul Zamasu and Jiren only add to the pile. You can jump from Low 2-C to 2-C over time, but not 3-A to 2-C without feats.
Except we're saying these feats were Low 2-C anyway, so our points still stand.