This isn't true at all. The 12 is going to sell better than the Mini/12 Pro/12 Pro Max, because it's going to the sweet spot for most consumers.the mini/Pro max will outsell the 12 so they're trying to get the margins up
Per Ming-Chi Kuo, Apple shipments for this generation are split as iPhone 12 at 40%, with iPhone 12 mini/Pro/Pro Max all at 20% each.