With regards to competency based assessment, you can find tools such as simulations/roleplays/written exercises etc.
However, times where competency model is designed in-house (post competency mapping exercise) it is difficult to find tools in a single place. It prompts you to source tools from mutliple sources or tweak the tools to cater it to your requirements. In which case one has to conduct a pilot for the testing the tools prior to finalization.
Further the choice of assessment tools is also dependent on the Type of Competency Model (Functional, Managerial Level etc.)
You can check SHL, Hall Marketing amongst the few consultants who may offer simulations/execrises based on competency models.
thanks & regards