That would be a foolish thing to do!
Keep the job and study hard to prep for technical interviews with other companies.
That means sacrifice! Sacrifice in time...for your job, family, hobby/free time. Weekends and after work for prepping. 3-6 months of hard prep.
You will be perpetually tired, anguished and impatient but if you don't train for the championship fight, a FANG interview will humiliate you and additionally penalize you ONE year from applying again. So train to WIN and for that you'll need MONTHS of prep.
Remember that it's not that hard to get an interview with a FANG with a recruiter, but it WILL be challenging passing the tech questions which have to be nearly 100% satisfactory. The most respected one at the moment is Leetcode but there are others. Google this information and look at support forums with people that exclusively talk about beating these interviews--no different than an SAT prep, this time just geared to FANG.
So yeah, don't quit your job unless your job s---s so much energy out of you that you really can't prep. That would be the only reason to quit. But you won't conclude this until you've been prepping for several weeks. And please don't arrogantly think you're all that and wing an interview with a FANG! You will get eaten alive!
Employment aside, your tech skills should always be FRESH! Depending on Juniper group, you could be eroding to irrelevance (or not). So it could be an imperative thing to move for long-term career survival. After all, how can you convince FB or G that your legacy support coding will help them in building their product? Careers as an SWE are short due to technical irrelevance, so you must be constantly stepping up like a musical artist (ie you're 80's metal won't be relevant in an R&B world).
So start first by prepping and then taking it from there whether your obligations to prep can be serviced enough with a job in hand.
Good luck!