Do I need to sharpen new chisels before using them?

Yes, in almost every case. The consistent message across r/handtools and r/BeginnerWoodWorking threads is that even mid-priced and premium chisels arrive with grinder marks on the back and an edge that won't pare cleanly. Plan on flattening the back on a coarse stone or sandpaper-on-glass and honing the bevel before first use.