I can't help much without seeing your code, but mql5 does have a similar Highest function.
Important to note this function does not return the price value, it returns the candle ID, so you need to finally call iHigh() after getting the ID.
https://www.mql5.com/en/docs/series/ihighest
And since we are on Fxdreema, there's a dropdown menu option as well:
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