The answer is right there in your own figures. the higher the leverage the less margin you are using. Less likely to get a margin call assuming you don’t use that leverage to open more and more trades at the same time.
The general rule of thumb is no more than 2% total. so if you had two trades open then each one should be risking 1% of your account. And that would be 2% of the account balance. so if you had 5000 in your account then if your trade hit its stop loss then you would loose 2% of the 5000.
You have to adjust your trade size based on how big you think your stop loss should be and how much a pip is worth to make it equal 2% of your account.