This and that should NOT be used to express "to what extent." It is NOT ever correct to say
...It was not that bad.
...I didn't expect it to be this easy.
Instead, you want the word so, which is what is called an adverb of degree, telling "to what extent."
...It was not so bad.
...I didn't expect it to be so easy.
Isn't this stuff fun?
Happy punctuating!
Margie