Sequels you wouldn't know are sequels from the titles

Similarly, the early Ellery Queen novels had a nationality in them:
The Roman Hat Mystery—1929
The French Powder Mystery—1930
The Dutch Shoe Mystery—1931
The Greek Coffin Mystery—1932
The Egyptian Cross Mystery—1932
The American Gun Mystery—1933
The Siamese Twin Mystery—1933
The Chinese Orange Mystery—1934
The Spanish Cape Mystery—1935

Their next novel, Halfway House was a change in how Queen was portrayed: they wanted to move on from the puzzle tales they had used previously. It was the last with the “Challenge for the Reader” gimmick and started concentrating more on character. They did suggest the title could have been The Swedish Match Mystery but clearly were giving up on the theme.

Later novels gave up on the nationality titling, so this fits the OP, too.

Sammy Davis Jr and Peter Lawford starred in Salt And Pepper — where the black guy is Salt, and the white guy is Pepper, and don’t worry, the movie will pause to explain how that’s a joke — and then they returned for One More Time, which, yes, arguably fits as a sequel title, but only in the sense that it would’ve fit all sorts of stuff as a sequel title.

Annie Get Your Gun . . . One More Time
Batman Returns . . . One More Time
Cry Macho . . . One More Time
Déjà Vu . . . One More Time

April in Paris . . . One More Time

It’s sort of like the Sidney Poitier/Bill Cosby film Let’s Do It Again (1975). You could stick that on the end of a lot of other film titles.

Let’s Do It Again isn’t really a sequel, but the three Poitier/Cosby films Uptown Saturday Night (1974), Let’s Do It Again (1975), and A Piece of the Action (1977) are, as Wikipedia puts it, viewed as a trilogy, even though the characters have different names in the three films. And it’s kinda hard to see the title of that second film as not suggesting that it’s some kind of sequel.

Don’t forget the final act of the trilogy. Not as popular, but still a good romp.

I guess there’s also college-age Kurt Russell’s temporary-superpower hijinks by way of invisibility serum in NOW YOU SEE HIM NOW YOU DON’T — you know, before he briefly became THE STRONGEST MAN IN THE WORLD, but after THE COMPUTER WORE TENNIS SHOES.

That leads to The Absent-Minded Professor and Son of Flubber, where you wouldn’t know the second was a sequel if you hadn’t seen the first.

And Son of Flubber sounds like it should be a sequel to Flubber, which was in fact a remake of The Absent-Minded Professor.