A decent universal adapter is one of the best small investments a traveler makes, and the market splits into two philosophies. Multi-region universal adapters combine the major plug systems, the flat American pins, British three-pin, European rounds and the angled Oceania type, into one sliding block, usually with USB ports added.
Features worth insisting on regardless: a genuine safety certification mark, built-in fuse, shutters over the socket holes, and multiple USB ports including at least one USB-C with decent wattage, since that alone can charge phones and even laptops and reduces the plugs you need. Grounded, three-pin support matters for laptops with earthed plugs; the cheapest universals are ungrounded.
Two honest warnings: adapters change the plug shape only, never the voltage, so single-voltage appliances still need a converter or replacement; and the very cheap no-brand universals sold in tourist areas are loose, flimsy and occasionally unsafe. Buy a reputable one before you travel, and pack two, because one always stays behind in a hotel wall.