This is not really quite right.
High leverage means that your broker only reserves a small balance from your account for initial margin and vice versa. Lowering leverage means that your broker will lock up a larger amount of your free equity against your position. Leverage is the measure of what proportion of the nominal amount of the position size is locked up, not the ratio of your total capital to nominal value.
For example, if your leverage is currently 200:1 and is then reduced tp 30:1 then your margin requirement increases by 6.67 times:
1 mini lot of EUR/USD = 10,000 units
If we assume a price of 1.17000 then your margin will be:
With 200:1 leverage = 10000 / 200 *1.17$ = approx 58$
With 30:1 leverage (as with ESMI) = 10000 / 30*1.17 = approx 390$
So for each microlot that you open you will need to have an initial margin of approx 39$. So 0.03 lots is going to need an initial margin of approx 117$ compared with an initial margin of approx only 18$ with a typical 200:1 leverage. This is a big chunk out of a 250$ account size just for the initial margin.
This is why leverage is such a big risk if it is abused - because with the same amount of capital, with a leverage of 200:1 you can open a position size that is 6.67 times larger than with a 30:1 leverage