Another household may have different rules about shoes, pets, food or which rooms visitors use. Tell your child about the relevant differences before arrival, while keeping the explanation short enough to remember. A long list of everything they must not do is unlikely to guide the actual visit.
Ask the host about arrangements that matter to your family. Check whether pets will be present, where children can play and what supervision is expected. Do not assume a home is arranged for young children because another child lives there; ages and needs may differ.
Choose a few concrete expectations
You might explain that shoes stay by the door, food is eaten at the table and a particular room is private. Tell the child what they can do as well as what is off limits. Bring a suitable small activity if the visit is mostly an adult conversation.
Avoid promising that the child will play with every item they see. The host's child may have personal toys they do not want to share. Help arrange shared activities without treating another child's possessions as communal entertainment.
Discuss greetings in a way that respects the child's boundaries. They can acknowledge a relative or host without being required to hug or kiss. Offer a wave or spoken greeting if that suits the child, and communicate this to adults who may expect physical affection.
Support the expectations on site
Stay attentive rather than assuming the host has taken over supervision. Give a quiet reminder or help the child move to another activity when needed. If the environment presents hazards, address them directly or change the arrangement; a rule is not a substitute for making a young child's space suitable.
Keep the visit's length realistic. A child who has managed an adult setting for a while may need a break or an earlier departure. You can thank the host and leave without turning tired behavior into a public lesson.
Afterward, mention what worked and any change needed for next time. The goal is to help the child navigate a different household respectfully, while recognizing that the adult remains responsible for preparation, support and the decision about how long to stay.