Hi Taner,
Yes, you can definitely do this. If you’ve not done so already download Workflow Commons from Marketplace
https://marketplace.mendix.com/link/component/117066
You have two options, directly assign the task to the user in the General tab of the ‘User Task’ within the workflow, you can use an XPath or Microflow to select the user or group of users.
https://docs.mendix.com/refguide/user-task#user-assignment
Also, in Workflow Commons there is this Microflow ‘ACT_UserTask_AssignToUser’ that you can use.