The island nation commonly identified as celebrating New Year's Eve first among permanently inhabited places is Kiribati.
Kiribati includes the Line Islands, which use UTC+14, the world's most advanced civil time zone. Because of that position on the international date line, inhabited parts of Kiribati enter a new calendar day before most other populated locations. Kiritimati, also known as Christmas Island, is the best-known example.
Kiribati shifted the date line around its territory in 1994 so that its islands would share the same calendar date. Before the change, the country was divided by the date line, making government and communication across the islands inconvenient. The adjustment helped unite the country administratively.
“First” depends on the wording. Kiribati is generally first among permanently inhabited countries and places, while ships, research stations, and uninhabited islands can create different technical comparisons. Samoa changed its side of the date line in 2011, but it does not use UTC+14 year-round in the same way as the Line Islands.