Need help in using Field Parameter in Top N filter and Conditional Formatting

Hi kc_1116 ,

In order to create conditional formatting for your bar chart, you can create a measure like below:

Selected Metric Value = 
VAR Selection = SELECTEDVALUE('Metric Selector'[Metric Selector Order])
RETURN
SWITCH( Selection,
    0, [M_IRR],
    1, [M_DPI],
    2, [M_RVPI],
    3, [M_TVPI],
    [M_IRR]
)

Then you can apply conditional color formatting in the bar:

Set the conditional formatting like below:

The resultant output is as shown blow:

I have attached an example pbix file for your reference:

Best regards,