Respect for elders runs deep in most of the world, and the gestures differ beautifully from place to place. In India, touching an elder's feet is a traditional sign of respect, and younger people often add ji after names or use words like uncle and aunty even for non-relatives. In East Asia, bowing depth and order of greeting reflect seniority, and elders are served food first and addressed with honorific language. In many African and Middle Eastern cultures, standing when an elder enters, greeting them first, and using both hands to give or receive items are standard.
As a visitor you are not expected to perform these perfectly, but a few basics translate everywhere: greet the oldest person first, stand to greet them, avoid interrupting, offer your seat, and use titles rather than first names until invited otherwise.
Authority figures like officials, teachers and religious leaders usually receive similar formality. Watching how locals interact for a few days teaches you more than any guidebook, and people notice and appreciate the effort.