For gamers who want to change the number of sockets for Diablo 2, you’ll be glad to know that there are several ways to do this.
If you want to know all the options, here is a complete guide on how to change the number of sockets for Diablo 2.
How Can You Change the Number of Sockets for Diablo 2?
You cannot add or remove sockets from an already socketed item, but you can add sockets to unsocketed items.
The Horodric cube and Larzuk’s quest reward are the two major ways to socket white items and both require unsocketed items. Because the Horodric Cube recipes only operate on non-superior items, superior items with less than max sockets are important if they have the correct number for a popular item.
Larzuk's Quest Reward
Larzuk is a good choice for socketing a white item on occasion, although infrequently. He’ll give it the greatest amount of sockets possible, which is determined by item type and item level (which is hidden but can be inferred if you know what monster dropped the item).
The usefulness of this is restricted because you can only socket three items per character at Larzuk (one per difficulty as a quest reward), and it’s more common for items to require fewer than the maximum sockets  to reach their full potential.
Because most good armor rune words require three sockets, three socket armor is far more valuable than four socket armor, while four socket armor is much easier to find.
However, because Larzuk is the only means to add sockets to superior white items, there are a few instances where spending your Larzuk socket on a white item is preferable to saving it for an otherwise unsocketable set or unique item.
These are only applicable to non-superior, non-low-quality white items. The number of sockets is chosen at random from 1 to the maximum for the item type (4 for body armor, 6 for weapons, 3 for helms, and 4 for shields), and then capped at the maximum for the individual item based on type and ilvl.
So, for example, a crystal sword dropped in Normal difficulty act 2 will get three sockets 4/6ths of the time, two sockets 1/6th of the time, and one socket 1/6th of the time, whereas a high-level circlet will get one, two, or three sockets with equal probability, because the maximum number of sockets for a helm is 3, but the maximum number of sockets for a weapon is 6.