At the start, when you begin exploring Teyvat, there is little to no grinding as long as you follow the Archon Quests and level your characters and weapons regularly.
But we should mention that the grind starts once you reach the later parts of the Archon Quests where there are many difficulty curves.
In most free-to-play RPGs, grinding is almost always a part of the game; so it's not surprising that Genshin Impact has that as well.