You can build custom logic as follows :
Create a Non-persistable object and add an enum attribute and set 20,50,100 values
On your page add a data source microflow & create RowManager object & return it.
Then add the Row enum attribute in a drop down.
Create on change microflow on the dropdown, and set the row number as per the selection.
Now add your data grids with in data view and display the grid based on row selection number with the help of grid visibility.
Hope this is helpful!
for example if your row numbers are 10,50,100 then add three data grids.
Update the visibility for each data grid based on row number selections and also set the same number of rows in the data grid.
For example if the row number selection is 20 then :
Please refer on this screenshot @Srilatha
This is the screenshot I'm referring to @Srilatha