Hi,
there is blog article from @Hendrik_Naether1 on the data grid here: Cumulocity IoT Data-Grid Tutorial Series - Part 1.
Pagination is described in Part 2: DataGrid - Pagination and tells:
You can set a page size of 10, 15, 20, 30 or 50 elements per page. If you choose any other number, the grid will fall back to 10.