@rashida It's hard to know without a formal assay of your system's levels. There is a test, and it will cost you, to establish your body's interstitial and cellular levels of Mg. The blood test is not a great indicator...you need a special diagnostic called an RBC (red blood cell):
https://biologyinsights.com/how-to-check-your-magnesium-levels-what-the-results-mean/
But what if your Mg levels are already at the high end of the 'normal' range? Neither of us knows. Would jumping up to 200 mg make a difference? No, not if your kidneys are dealing comfortably with any excesses....which 'sound' kidneys will do, day after day. If you have marginal or poor kidney function, excesses of potassium (K) are most problematic, but Mg might pose a risk as well. So, I cannot answer your question with a simple 'Sure, go ahead and try it,' as it might be dangerous (not to mention I am not a doctor, and certainly not your doctor).

Most healthy people can take upwards of 400 mg of Mg daily and it won't affect them...they'll just pee it out. I know one person who mixes his own magnesium drinks because his kidneys dump it all. He ingests 1000 mg daily!! If he DOESN'T do that, he experiences more AF. I would strongly recommend you not take more than 400 mg daily, but only if you do know for sure your kidneys are robust and that you aren't already skirting around the highest recommended sustained levels in your blood serum.