"is taller" is a grammatically correct and usable phrase in written English.
It should be used when comparing two people or things in terms of height. Example: "Josh is taller than Connor."
Dictionary
is taller
adjective
Having a vertical extent greater than the average. For example, somebody with a height of over 6 feet would generally be considered to be tall.
Exact(60)
Leon is taller and more earnest.
The wicket is taller than the batsman.
In the south, the forest is taller and is evergreen.
The dukduk is taller than the tubuan and is faceless.
The wolf's body is taller and wider than the coyote's.
Mr. Davidson said she is taller than he remembered.
"It is taller and bigger overall than the Sphinx.
Even then, at age 3, Woodrow is taller.
Gabriel is taller and quicker than Taylor, though.
But Grant is taller and outweighs him by 10 pounds.
An example of a reasoning problem based on a linear syllogism is: "John is taller than Bill, and Bill is taller than Pete.
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Since I tried Ludwig back in 2017, I have been constantly using it in both editing and translation. Ever since, I suggest it to my translators at ProSciEditing.

Justyna Jupowicz-Kozak
CEO of Professional Science Editing for Scientists @ prosciediting.com