Can I take restaurant orders in a WhatsApp group?

You can, but it is a poor fit. Everyone in the group sees every message, so orders and addresses get mixed up. Announce in the group, order one to one.

• A WhatsApp group can hold up to 1,024 members. Once it is full, no one else can be added.
• Every member sees every message, so one customer's address and order can be seen by others.
• People can set who may add them to groups, so many will not join a group you start.
• Post the menu or an order link in the group and ask people to order in a private chat or on the link.
• Keep one order per chat so nothing is lost when the group gets busy.