The phrase "a large extent of" is correct and usable in written English.
You can use this phrase to emphasize the size or degree of something, usually in a negative context. For example, "The accident caused a large extent of damage to the city's infrastructure."
Their courtship consisted, to a large extent, of traveling to antiwar rallies and teach-ins across the Midwest.
Cameron knows that this appalling end to his six years as prime minister is to a large extent of his own making.
To a large extent, of course, it was because of his natural ability: he is quick, technically adept and has a powerful shot.
On the other hand, a large extent of the English church was left to the government of William I and Archbishop Lanfranc of Canterbury.
The Midi side is made up, to a large extent, of the many English expatriates who have moved to the area.
The only difference now is that the G.O.P. is in a weaker position, having lost control not just of Congress but, to a large extent, of the terms of debate.
One Army official learned only two words of German during his fourteen-month stay there; of the Military Government force consisting, to a large extent, of floaters and misfits; of intramural animosity, bickering and gripes among the Americans.
For employees from almost every company in lower Manhattan, there is still no indication of when they might return, nor, to a large extent, of what they might find when they do.
This weakening or aspiration of s before a consonant or in final position and the weakening or disappearance of d between vowels (to(d)o for todo) is also a feature of Chilean pronunciation, and to a large extent of the Argentinian accent too, except in deliberate and more 'careful' speech.
Aragonite (CaCO3) is an example of an inorganically formed mineral that also has an organically produced, yet otherwise identical, counterpart; the shell (and the pearl, if it is present) of an oyster is composed to a large extent of organically formed aragonite.
To a large extent, of course, the answers don't matter.
