I have an iPhone 8 Plus prepaid by boost Mobil do you take this one for trade in? II am interested in the new iPhone 12 The biggest the better

1. This is a user to user forum, you are not addressing Apple here directly.
2. Yes, Apple can take Apple devices for trade in regardless of cellular carrier.
3. Apple only sells the regular iPhone 12 and 12 mini at regular retail now, but no longer sells the larger iPhone 12 Pro Max (largest one they made). You can Purchase a regular iPhone 12 (largest one currently available) form the following link and start the trade in at the same time too. Link-> Buy iPhone 12 and iPhone 12 mini - Apple
4. You can purchase an iPhone 13 Pro Max (largest iPhone currently available) here: link-> Buy iPhone 13 Pro and iPhone 13 Pro Max - Apple
5. You can compare iPhone sizes here: link-> iPhone comparison - Apple.com

Thank you for contact the Apple support community

You can find out how the device replacement works through the following link:

https://www.apple.com/shop/trade-in