All standard .NET formatting features can be used to specify how the OPC values should be displayed.

How to configure this feature:

Bind the OPC-DA item (or OPC-UA node attribute) to the TextBox or similar control as usually.

Then, use the "Edit Live Bindings" command on the control, and set the StringFormat property on the item binding as needed, using all standard .NET formatting capabilities. {0} in the formatting string represents the value to be formatted. For example, {0:F3} means a floating point value formatted with 3 decimal places.