No, that's not grammar checking, but spelling mistakes that turn out to be real words!

If you misspelled "college" as "collage", or you misspelled "three" as "tree" the word you typed incorrectly happens to be an actual word itself! Correcting these types of errors is called "real word spelling correction".

Real-word spelling errors are words in a text that, although correctly spelled words in the dictionary, are not the words that the writer intended

https://www.researchgate.net/publication/221628953_Real-Word...

And even if there are several approaches evaluated, the problem is far from solved.