The default position in Islamic jurisprudence regarding the fixing of prices for goods and services is not to do so.

When you inform certain Muslims, typically those sympathetic to socialism, about the hadith that emphasizes the negative consequences of fixing prices in a free market, stating that it leads to injustice (to both merchants and eventually the buyers) they often respond by asserting that the second Caliph of Islam, Umar Ibn Al Khattab RA, was in favor of price fixing.

They reference a narration in which he instructed a merchant to increase the price of his goods, but conveniently omit the fact that Umar RA later approached the same merchant and expressed regret over his earlier command, uncertain if it was the correct course of action.

The attached screenshots display a conversation between Shaykh @DrShadeeElmasry and @SafdarAlam, discussing this very topic: