Hand in hand: When men and women hold hands, it will make people feel that the intimacy between them is very high.
Walking with arms around: Walking with arms around is a way to show intimacy. This kind of behavior will make people feel close to each other.
Snuggle up to each other: When one person snuggles up to another, this behavior will make people feel close to each other.
Kissing: When a boyfriend and a girlfriend kiss in the park, it's easy to make people feel close to each other.
Expressing emotion: A girl can show the intimacy between her and her boyfriend by expressing her feelings. For example, she can say something sweet, or show her concern and love for him.
It should be noted that everyone's behavior habits and cultural background are different, so there will be some differences, but the above behavior can be regarded as a way to express intimacy in most cases.