It would be cool to have an option that increases the Main Deck limit to let’s say 100-120 cards and the Extra Deck limit to let’s say 30-40 cards. It can be available as an option only against the AI.
There is already double deck format. This format forces both players to have 2- 50 card main decks that become their 100 card main decks, and up to 15 card extra decks to become their up to 30 cound main decks.
And I already reported that the Double Deck format is not working: