It will be for all words except one situation where it is followed by a vowel in the next syllable. For example
있다 - sounds like 잍다
있어 - sounds like 이써
So when it is followed by a vowel is it pronounced as normal
#ㅅ as the final consonant
gaunt scroll
eternal river
Correction:
있다 is pronounced as 읻따
This is because only the consonants ㄱㄴㄷㄹㅁㅂㅇ are pronounced at the end of a letter. (It's called 음절 끝소리 규칙 if you want to research more about it)
So 있다 becomes 읻다.
However there is 1 more process it goes through to make the pronounciation easier; it's called "된소리되기".
So basically what this is is that when the final consonant and the first consonant of the next letter are one of ㄱㄷㅂㅅㅈ, the first consonant of the second letter becomes ㄲㄸㅃㅆㅉ (in some conditions), leaving you with the final result of [읻따].
So 슷 would also be pronounced as 슫, not 슽.
gaunt scroll
So 슷 would also be pronounced as 슫, not 슽.
But doesn’t ㅌ in the 받침 position make the ㄷ sound anyways?
eternal river
well yeah