Hi and sorry for the delayed response you can do that by including more cases inside the if statement like this
{% if card_product.handle == 'A' or card_product.handle == 'B' or card_product.handle == 'C' %}
Customize
{% endif %}
or this way
{% assign custom_handles = "A,B,C" | split: "," %}
{% if custom_handles contains card_product.handle %}
Customize
{% endif %}