That's simply not true, we know barely anything about the 23rd century, the majority of the TOS adventures where isolated incidents, we got to see the adventures of one ship over just a few years.
‘This could lead to the end of the federation’
‘The very universe is at risk’
‘Earth is under direct threat of imminent destruction’
Ignoring that heroes usually (but not always) save the day, these sentences can never ever be spoken in DSC and have any real stakes, while it is part of Prime continuity. Does a story have to have such high stakes to work in Trek? No. But a fair chunk of them do. All good things. The dominion war in DS9. Best of Both Worlds. Anything with Species 8472. A chunk of all Borg stories tbh. At least two of the movies.
Some will say ditch the continuity. But (a) they haven’t and (b) the continuity for many is a big part of Treks appeal.
It’s an inherent problem with prequels. You can see what you like about Lucas, but he at least made sure there were stakes in his prequels, even though we knew what was coming. In fact he made that tension part of the story.
The one thing you can do is make characters that we care about to put in jeopardy or watch grow.
Which is why I think moving away from the Klingon war stuff is Key to DSC continuing.
It’s also why the Picard series will do well...it already has a character people have some attachment to, and can also have big stakes if it needs them. It’s likely of course Picard will die in the end, it’s a trend for actors with cult characters. I was actually surprised when Deckard didn’t die in Blade Runner 2049.