Based on the feats and lore of the God of War series, Kratos could most likely destroy a mountain with a punch if he put his full power into it. However, in the games, his power is typically scaled down for gameplay purposes to maintain a challenge.

Here is an examination of his feats and why mountain-level destruction is well within his capabilities.

Evidence from Kratos's canonical strength
>Overpowering Titans: A younger Kratos has shown incredible strength against beings larger than mountains. He fought and overpowered the Titan Atlas, who was cursed to hold up the infinite Earth, heavens, and cosmos.

>Controlling his strength: As an older and wiser Kratos, he consciously restrains his true strength so as not to cause collateral damage to the realms. In the 2018 game, developers considered a scene where Kratos would punch a mountain thrown by Baldur and split it in half, but scrapped it because his character was supposed to be rusty and reserved.

>Continental devastation: The first clash between Kratos and Baldur in the 2018 game was so powerful that it tore apart the surrounding continental landmass. This feat is "far bigger in scale than moving or destroying mountain passes," according to some fan analysis.

>Overcoming cosmic beings: Kratos has defeated beings like Kronos, who was a conceptual entity of time and space, and Thor, who could shatter the World Tree (Yggdrasil). These feats operate on a scale far beyond just raw physical strength.