Does Amazon Lex V2 have support for response cards using the UI?

Amazon Connect does not support Lex response card feature. You have to use the feature in Connect call Interactive Messaging, this xml output can be created using Lambda.

Here is the documentation for it: https://docs.aws.amazon.com/connect/latest/adminguide/interactive-messages.html

and here is an example blog https://aws.amazon.com/blogs/contact-center/easily-set-up-interactive-messages-for-your-amazon-connect-chatbot/

this is different from Lex response card feature

In Lex V2, cards can be added to any prompt or response. The ability is available under More response options or More prompt options settings. I am sharing some screenshot for how to add response care in slot elicitation prompts.

1. Click on Advanced option under the slot setting to open the side panel with different configurations.
2. In the side panel. Click on 'Slot prompts' to expand the section. In the expanded section click on 'More prompt options'

3. In the new view. Click on the Add button on top right of Slot prompts settings to open a drop down and select Add card group

4. This should add a new card group to the message list. Configure the card group and save