I'm not sure if I can use Stack Exchange API to build a https://www.gharchive.org like project?
I studied the API throttling documentation but I am not sure.
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Well, you certainly can.
But given that you're only allowed 10,000 API calls each day, assuming you have a key, you can barely fetch each new post (question or answer) on a regular day. These numbers show exactly that. Beyond that you are subject to throttles and IP rate-limits. If you plan to use every 10,000 allowed calls, you can have a call every 8 seconds. Making calls at a higher rate makes no sense as you will run out of API quota before the end of the day.
Beware that the throttle guidance talks about both IP based and dynamic throttles. Those are different things and applied separately. See "backoff" missing when updating questions and What's the relation between access_token, key, quota_max, and throttling? or search in the rate-limit tag
You might be better of to leverage the already available data sources for data-analysis, be it the Stack Exchange Data Explorer (refreshed weekly) or the Stack Exchange Data dump (refreshed quarterly).