Some amazing early tile yield potential: incans if you get decent mountains + an aqueduct. The farm is +1

itself, on a hill which is +3 yield total usually, +1

per mountain, +2

for an aqueduct, available right away.
The spanish mission on a foreign continent is also a yield monster. Suppose you drop one on a grassland next to a holy site and a campus; 2

for the grassland, plus +2

base, plus +1

,+1

,+2

for the foreign continent, +1

for each holy site or campus, +2

more at cultural heritage late game. That right there is a 3

,1

,4

,4

tile. I should point out that generally on tiles, 2

gold = 1

food or

production, and 3

gold = 1

science,

culture, or

faith, so that 4 faith and 4 science is really worth a lot!
Also, the dutch polder in lakes specifically- if you get a convenient 3 tile triangle lake, for example, those suckers can just dump yields on you.
See the lower left, top center, and middle right of the image below. (This game has Auckland city state in it, which gives +2

production to water tiles.)
Australian outback Stations can also give you stupidly high yields once you get the late game techs that unlock their adjacency with pastures and themselves.
By far the best yields you can get on a tile though, would be getting a decent sized desert and putting down some nazca lines (city state improvement) on it. They offer +1

, +1

to each adjacent desert tile,+1

if it's a flat tile and +1

more if its got a resource. The catch is that you cannot work a tile with a nazca line on it, so if you had a hypothetical flat desert tile which so happened to have a resource like, say, aluminum on it, and built a mine and surrounded it with 6 nazca lines; and you had Petra+Ruhr valley in that city, then that single tile would be worth 8

,12

,2

,1

,12

. (But if you have a big desert the best layout to maximize the total yield from nazca lines is to build a grid of them where each empty tile has 3 nazca lines around it, but no nazca line touches another one.)
Alternatively, turn up disasters to 3 or 4 and literally any volcano natural wonder that's always active can become an absolute yield juggernaut by late game, since tiles can get boosted endlessly. It's crazy.
Not including district yields, because I have already seen the video on plus 50 IZ
50?
50?! We can do
so much better. (And now we can do that with just 3 cities instead of 6.)
+111 production from this single district. This is what we call
TEUTONIC PRODUCTION
Pssst... Hey kid, wanna make some real money?