It depends on what those existing 100 articles are talking about and whether they're targeting low-competition, highly relevant niche keywords.
If you're just posting 100 articles that you think are “good,” it’s anybody’s guess if you will build up enough domain authority.
I would suggest that you run an audit on the URLs of your existing content using tools like Ahrefs or Semrush and see what kind of keywords they rank for or are related to.
Next, reoptimize each of those 100 articles to a better target keyword, as recommended by those SEO tools that I just mentioned.
How do you do this?
Well, you can do this by guessing, or you can use a tool like Surfer SEO.
What you do is you take the existing article, plug it into Surfer SEO, and see if the keywords on the right side are turned green.
Then, tweak your existing text—maybe extend it, lengthen it, add more images, create more headings—and do what you need to do to get all those indicators on the right side to turn green.
That's how I would do this.
I've done this before for previous projects, and let me tell you: for keyword targets that have manageable levels of competition, I've been able to rank them quite high in a fairly short period of time.
Also, the technique that I outlined above also works well if your site has been trapped in the Google sandbox for more than eight months.