Caution: The following contains spoilers for Final Fantasy VII Remake.
Once you complete Final Fantasy VII Remake, you get the option to skip around the game using a Chapter Select feature. You also unlock a new difficulty, "Hard," which prohibits the use of items in battle, and MP can only be restored by smashing crates, slowly regenerating it in battle by forgoing spells, or clearing the chapter you're on. Bosses also hit harder and more frequently, but the overall strategy isn't too dissimilar to Normal mode. However, you'll find yourself needing to prepare for various fights a bit more carefully.
Luckily, if you've been using Assess in your first playthrough, it'll help you build a strategy ahead of time by carefully selecting your materia and equipment loadout. For bosses who have a vulnerability to one specific element, you can socket that corresponding materia while beefing up your party with HP Up, Parry, Steadfast Block, and so on. Also, having foreknowledge of how particular boss phases proceed helps too.
Given that MP doesn't recover fully in any given chapter, you'll find yourself having to carefully consider when and where you use spells. Suddenly, busting out a Firaga spell against an enemy weak to fire magic seems