An orphan shows up one day with no records of who they are and they cannot be identified amd the orphan doesn’t know who they are
Say they wash ashore or some countries child protective services finds them
Do they get citizenship ?, what happens to them ?
If the country has jus soli, yes they are citizens.
If the country only has jus sanguinis, well depends on the country. In some jus sanguinis countries, they might give citizenship to children born in the country, if they aren’t eligible for any other citizenship. Otherwise, they might stuck in statelessness for a while.
I can’t speak for other countries, but if this was China (where I was from). And the orphan looked Chinese (or at least one of the ethnic minorities of China), they might be given Chinese Citizenship after going through some bureaucracy, and the government would just assume the kid’s parents are Chinese (and therefore get citizenship via jus sanguinis). If the orphan didn’t look Chinese, they might just do a DNA test, then deport to which ever country the DNA say they’re from. Its a homogenous society, they are not gonna let foreign children there.
I assume that other countries, if the country never had much immigration to begin with, and the kid does not look like the people of the country, its likely just deportation to whatever country they think the kid is from.
If its a immigration country, its either jus soli, or if jus sanguinis the orphan would just have to hope the country is accepting enough to just give citizenship.