There is no current way to give all access flags at the same time. I'd suggest simply give them the important ones, and go from there depending on what's needed.
There unfortunately isn't an "all" flag at the moment, although it certainly has been thought off and might get added in the future. So for now, you will have to give them all flags one by one
People have suggested this and it may or may not have been approved. I would like it if it happened buy we will see.