How to get plastic cards instead of metal cards by default?
 

Metal cards don't seem to work as well when making contactless payments, likely because metal blocks radio signals.

How can we request Amex, Chase, Citi to send us plastic cards instead of metal cards?

This will be a product by product answer, because in many cases a plastic version does not exist. The universal workaround is to add the card to Apple Pay or Google Pay account, and use a phone or watch to make contactless payments.

In the case of American Express Platinum you should be able to order a supplementary Gold card, which is plastic, and use it rather than the Platinum card for contactless payment, but you would still need the metal Platinum card for lounge access.

https://www.flyertalk.com/forum/amer...tal-cards.html