Hi! With cyrillic letters, which can be found for example in the Russian language, there is no option to spell an accent marked vowel, at least using the Russian keyboard layout. Google's Keyboard, which name is Gboard, has this option. These keyboards are quite similar in the end, but I'd think it would be beneficial to have this option also for the Samsung one, at least as an optional option. On Gboard, you simply long press the vowel to bring up possible letter variants, which display the accented option. Accents are important to spell down in some situations, like when learning a language or teaching another person.
If you have the ability on GBoard, use GBoard. I find you can do the same with Samsung keyboard. Long press the letter in question, an your accent choices come up.
