Generally single (unmarried) sefardim keep one day, and the minhag among Ashkenazim is those who have a chance of returning to chutz la’aretz hold 2 days – I have been living here for 2 years now and we keep 2 days. There are different factors involved, and each person should ask their LOR, but this is the generally prevalent minhag AFAIK. For a lengthier discussion there’s a Sefer called Yom Tov Sheini K’hilchoso.
There is a concept of 1 1/2 days YT. It is a little tricky, but basically we’re mechuyav in the lo sa’asehs but potur from the asehs, meaning we can’t do melocho but we don’t have to make kiddush. I believe there are some opinions that a person from EY could do melocho on the second day of YT in private, but I’m not 100% on that.