Your height also dictates a shoe size so instead of looking at adult look at child sizes
True paddock boots will work with 1/2 chaps, look appropriate and fit correctly....
Most websites have measurements available for the manufacturer and style as each can be different.
If you are really set on tall boots they too come in short, average and tall sizes and again, each manufacturer and style do fit differently.
If you are going to do tall boots I would suggest field boots as they have ankle laces that can snug a bit of excess from the ankle area you don't accumulate in paddock boots.
If you wear adult size shoes and find the boots still to tall for your leg then they can be cut down by a shoemaker, aka cobbler or by who does saddle repair at a good saddle shop.
Remember tall boots must be higher than your knee joint bend to start or when they break in and "drop" they will be to short and uncomfortable when riding.
Good luck in your search.