Hey, @vwoo,
Do you mean customize the text of the invitation? There are a variety of places where a "Copy invitation" link will get you a full-blown set of instructions like this:
I usually do some "light editing" on this after pasting it into a document or email.
However, if you're hoping to customize this text's appearance or content, I don't think it's possible. There are customizations called "Branding" available for emails sent out via Zoom, but these require Business, Education, or Enterprise accounts with a Vanity URL. See the links @Ohkawa provided for more information.
