Of course not. I don't think any level of government can mandate (god, that word...) a holiday being a paid day off across the board.
Why not? The Paid Holidays we have now are because they've been mandated. Maybe mandated isn't the right word, but passed by law. If your state passes a law that states Juneteenth as a paid holiday, then it will be.
That's not true. There is NO holiday on which every employer is required by law to pay employees.
For starters, you have to distinguish between hourly employees and salaried employees. Salaried employees get paid regardless of when and how often they work. They are typically allowed a certain number of days off for vacation or sickness. Hourly employees, on the other hand, don't get paid unless they work, UNLESS...
Members of labor unions are different. Government employees are also different. Hourly employees in both of those groups may get paid for days when they don't work (and/or may be entitled to extra pay for working on certain days).
Now...there are federal holidays (11 of them): new year's day; MLK day; Washington's birthday (not presidents' day); memorial day; juneteenth; independence day; labor day; Columbus day; veterans' day; Thanksgiving; Christmas. Those are days when federal offices are closed. Whether hourly federal employees get paid for those days is something I don't know.
Each state also has state holidays. Most adopt most of the federal holidays and add a couple of their own: for example, California has Cesar Chavez day. Federal offices may be open on state holidays that aren't also federal holidays. Again, whether hourly state employees get paid on those days is something I don't know (even for California).
Each employer may have its own list of holidays. My employer gives us most of the federal holidays, but when I started, we didn't get MLK day or presidents' day. However, we have always gotten a "spring holiday," which always happens to coincide with good Friday. We also always get the day after Thanksgiving. I don't actually know if our hourly employees are paid on those days, but if they are, it's not because of any legal requirement that they be paid.