While there are already some of those functions built as mods to the game, one can not use mods while playing for the achievements
Pick a tool on the left hand side in the menu:
- Tile : Arrange copies of the blueprint in a grid. E.g. take a six electric miner blueprint and tile 15x15 to cover even the biggest resource fields
- Split : Split a large blueprint into tiles to make it easier to place in game
- Mirror : Mirror the blueprint either vertically or horizontally
- Upgrade : Decide what common upgradeable entities (e.g. inserters) to upgrade. Also supports downgrading (e.g. you have a great blueprint but not the tech yet)
- Landfill : Put landfill under a blueprint
Then paste the blueprint string either from the game or from a different place into the input field, adjust the settings, and finally copy the final blueprint and import it into Factorio