As others have said this isn’t the infinitely expanding manifold time of DC or MCU (pre Loki season 2).

SNW season two confirmed what we could infer from the premier of TNG when the date of WW3 had shifted back decades. It also happens to line up better with the understandings of modern physics.

The Prime Timeline in Star Trek is a resilient enormous river. It can be shifted a bit in its course, slip forwards and back.

BUT major events remain largely unchanged

• those changes that aren’t large enough to create a major fork shift to a very different future as in TOS City at the Edge of Forever

OR

• it takes an event of the order of the Romulan Supernova to create a new branch universe (Kelvin U).