Scene layer package—ArcGIS Pro | ArcGIS Desktop
Is the input a...
Select a multipatch, point, or point cloud layer as the Input Layer.
Which also has a link to
Create Scene Layer Package—Data Management toolbox | ArcGIS Desktop
Which has a whole load of requirements, with the final one being size related, because there is an extra step if it is greater than 1 GB in size.
Can you elaborate on the input?