The Horadric Cube recipe in Diablo 2: Resurrected for getting 4 sockets on a Paladin shield is:ДЎ Tal Rune + 1 Amn Rune + 1 Perfect Ruby + 1 Normal Paladin Shield (with required level and quality)

Alternatively, the Horadric Cube has the possibility of creating 4 sockets on a Normal white Paladin shield at level 26 or above, but the shield cannot be Low-Quality or Superior. This is the first quest in Act 5, Siege on Harrogath. It's very important to note that a Paladin shield must be at level 26 or higher to give 4 sockets as a reward from the quest. While Normal difficulty can only drop a 3 socket shield at maximum for the Paladin, the socket quest or Horadric Cube can be used to acquire the 4 sockets needed to insert the Spirit runes. The Paladin in Diablo 2: Resurrected is the only class that can acquire a 4-Socket Shield while playing on Normal. Players must be at least Level 25 to make Spirit. Having the shield instead of the sword means other classes can get better attack bonuses with other weapons. The Spirit Shield is favored over the Spirit Sword as it's an off-hand piece of equipment that doesn't need to be actively used to reap the most benefits. The Spirit Shield and Spirit Sword have similar stats but vary slightly.

A Normal white shield or sword with 4 sockets is required to hold the runes. Players need 4 sockets in order to insert the runes Tal, Thul, Ort, and Amn to make the Spirit Runeword in Diablo 2: Resurrected.

Diablo 2 larzuk socket guide