Вы можете изменить тело фигуры OHLC, используя метод setBodyFillStyle .
const series = chart.addOHLCSeries()
// Style a positive OHLC figure
series.setPositiveStyle( (figure) => figure
// Style the body of a Positive Figure
.setBodyFillStyle( new SolidFill({ color: ColorHEX('#E69965')})
)
// Style a negative OHLC figure
series.setNegativeStyle( (figure) => figure
// Style the body of a Negative Figure
.setBodyFillStyle( new SolidFill({color: ColorHEX('#E659A5')})
)