MacOS has an input method known as "ABC - Extended", which allows inputting most diacritics with any Latin letters. With it, "Alt" + various keys give a diacritic waiting to be composed, and pressing a letter produces the letter with the specified diacritic. For example:
Alt + E gives acute (´), which can be used to produce
Alt + U gives diaeresis (¨), which can be used to produce
Alt + C gives cedilla (¸), which can be used to produce
Alt + B and Alt + V give breve (˘) and caron/háček (ˇ) respectively, which can be used to produce Romanian
ă and Pinyin
My question: is there a similar way to input various diacritics on iOS/iPadOS? All of the system keyboards seem just to offer a limited set of accented letters.