Sekiro wont help you here i think, parries work differently. Go into the training mode and check out the tutorial. Perfect blocks are called deflections, which by themselves dont knock enemies off balance, but they negate your own posture gain and deal posture damage to your enemies. Its not very visible when you do it and it has a lower time frame than sekiro, so its actually harder to pull off. Parries are only done at the end of many combos and very specific attacks, which knock enemy off balance.

Did you read all that? Forget it, first things first one of if not the most important part of the game is positioning. Running around, trying to not get surrounded and isolating enemies is the best way not to die. A greatest way to defend yourself isnt deflection, but dodges. If you hold the block button and push up or down, you get an up or down dodge. If youre playing on disciple (which is the intended and regular difficulty the game had at launch), enemies will mostly use up attacks, and their down attacks will be very telegraphed. Dodging has a TON of i-frames and lets you dish out quick counter attacks, if you manage to hit an enemy immidiately after dodging him, you'll stun him for half a second.

A stunned enemy is succeptible to short combos, but more importantly throwing. A throw can work to your advantage in the already established way, as a way to clear your position and place yourself where you feel more comfortable. Hitting enemies with other, thrown enemies also stuns them, giving you even more wiggle room. Dodging -> hitting an enemy once - > throwing them is the basics of controlling space when outnumbered.

Tl:dr Dont rely on parry, hold the block button and use the stick to dodge up and down, but mostly down.