>>216381777 (OP)
they type in latin letters (pinyin) and then it gets turned into chinese character automatically or they chose the character from some given options based on the thing they wrote
same with japanese except it first turns the thing you wrote in latin letters to hiragana and then to chinese characters (kanji) if you chose to
koreans have their own keyboard tho they actually have an alphabet with letters that works similar to latin/cyrillic/greek etc. even though it looks different
they bunch them together to make square chinese character looking things for some reason