Yes, you have the option to "tune" the parameters of any obtained model in the leaderboard.
To display the advanced parameter settings, you can click to expand a model in the Leaderboard list, then under "Evaluate" you can click on "Advanced Tuning". A window opens displaying parameter settings on the left and a graph on the right.
Essentially, advanced tuning allows you to manually set model parameters, overriding the DataRobot selections for a model, and create a named “tune.” In some cases, by experimenting with parameter settings you can improve model performance. Please note that when you create models with Advanced Tuning, DataRobot generates new, additional Leaderboard models that you can later blend together or further tune.
Here's a page describing the steps including a video walkthrough: