If you are asking if there is a setting to allow spell checker to ignore quoted material, then to my knowledge the answer is "no."
The first thing one should do in a compose window, if the bottom quoted material is not needed to retain context for the reply, is to delete it. A CTRL+A followed by either the Delete key or backspace accomplishes this. Then the only thing the spell checker has to check is what you've written.
Brian - Windows 10 Pro, 64-Bit, Version 1903, Build 18362
Many of the insights of the saint stem from his experience as a sinner.
~ Eric Hoffer