Meet people in everyday situations, not very drawn to tourist attractions.
For an example. Not being from the US we are interested in your country as a different culture.
We have visited different US state capitols as they have ancient, modern and current history tied to them, and all have been magnificent buildings too.
Bob Dylan showed us an authentic honky-tonk, fantastic. Jeb introduced us to the juicy lucy, great evening and surprising. We were given a masterclass on the operation of a space shuttle by our now good friend Milton, who we met on the Southwest Chief.
We are interested in museums, sometimes. I have the barbed wire museum on my wish list as it's so improbable.
Train travel anywhere fits the bill as you never know who you will meet while the real world goes past the window. What 'local' people do and see, where they are is often interesting to us if ordinary to them.
Sorry for a non answer and I do thank you very much for asking, but there isn't a simple reply other than often the unexpected and the normal.
I do ask a lot of questions about the US on this forum, and every time a subject is discussed we take something away from it. Not always the intended but something we could never know without local knowledge.
Much appreciated
With a "non-answer" as you put it, you'd fit right in over in "The Building aka the Capitol"
Maybe this helps, maybe it doesn't, but I tried
I'll leave Old Sac out of this. Outside of the railroad museum which is well worth it, I'm not the biggest fan of it, I'd even go so far as to say you could skip it (Old Sac, not the railroad museum see that for sure), though the local tourist board will be after my hide for saying that. As the capital city of the state, the capitol building itself is a great thing to see. If you're here at the right time you could even sit in on an Assembly or Senate session or a hearing of one of the many sub-committees. Since a lot of people in town are in some way involved in government seeing the process at work is fairly interesting. The bear statue in front of the governor's office is also a popular photo spot. You might also recognize the portraits of a couple of our former governors.
A block south of the Capitol is The California Museum where they have some exhibits on the history of California and the state's Hall of Fame. East of the Capitol about a mile or so is Sutter's Fort which was part of the original settlement of the city. They do reenactments at times during the month which are fun to see when it's not closed down due to the public health crisis.
The Midtown neighborhood between the Capitol and Sutter's Fort is where a good number of the locals go as it's where the bar and restaurant scene is. If you're looking to mix with the locals and have a day to do it, that's the part of town to be in. It'd been doing pretty well until recent events and it's hopeful that it can rebound once things go more towards normal. One particular bar that's pretty popular, and near the Capitol, is a British pub called The Fox and Goose which also is a popular breakfast spot.
Otherwise, the city is really known for its outdoor spaces, trees, parks, and bike trails. While the downtown area doesn't roll up the sidewalks at 5PM anymore, it's still not the most vibrant area. However, if you want to get a feel for Sacramento, a weekday when the legislature is in session is best.