To start go to go to Pyramid .... good
Next, when you select difficultly obviously put it to Hard as the achievement description suggests, but then don't forget to change the drop-down box at the top to '3 Boards' before hitting Play
Now, you have two options ...
1 -
Play the boards as normal and clear all three, AFAIK all boards created in this way are solvable.
If you mess up you can 'Undo All' and start that Board again (it won't put you back at Board 1 if you hit Undo All on Board 3).
When you clear the third Board the achievement will pop when going back to the Home screen.
2 -
Use a solver, this is a good one that has a nice graphical look etc -
https://igniparoustempest.github.io/pyramid-solitaire-solver...Just remember to read the instructions on how to input the cards, using the letter T for tens etc.
To input the cards form the stock pile you will need to click through it and input them as you go, remember to hit 'Undo All' when you are done to reset the Board otherwise you might run out of stock pile refreshes
FYI -
When I have used this solver for hard/expert boards it has worked as expected, however I have never been able to use it for Grandmaster boards, it just hangs and eventually the tab crashes but for this achievement it should work OK