If you check Scatter Plots, as you zoom in the charts , the y axis scales to give you better perspective.
In OHLC and Candlestick charts, you can only zoom in by the x axis, therefore the y axis remains the same and bars/candles don’t adjust to your zoom.
I went through a lot of posts and github issues and couldn’t find any solution to this, but most of those were old, so maybe things changed from the past couple years.
This feature request has a long history that I believe is still open:
I honestly don’t understand how the rangeslider is even useful without auto-scaling the y-axis, but it’s something plotly developers haven’t considered a priority.