Definitely. There are a few microflows which cannot even have a Parameter
All others: the goal of a parameter is to pass a available value, object or list into the microflow. So that that can be used as context of the microflow. If there is not such available or needed, no input parameter is needed
I believe you can use microflows without parameters. However, you may have to retrieve the objects that you would like to use in your microflow.
Yes you can use the microflows without parameters