When using the Quartus® II software to generate design specific IBIS models, you have the option to Enable Model Selector. This option will generate IBIS models with all of the available drive strength and slew rate options available for a given output or bidirectional pin configuration.
However, the model index grouping is based on I/O standard, pin location, and direction. The drive strength setting is not part of the index grouping criteria. Thus, you will need to ensure the IBIS model you use for signal integrity simulation matches the programmable settings applied to the pin in the design.
For example, your project may use a 2.5V output set with a drive strength of 12mA. However, the default model set for this output pin in the model selector index may use a drive strength of 8mA (ttl25_io_d8_ms1). In your signal integrity simulation tool, unless you manually select the 12mA driver model, it will simulate the 8mA driver which is the default value used by the model selector index.