Here is the full list of all 45 Hogwarts Legacy achievements. It takes around 60-80 hours to unlock all of the achievements on Windows.
Find the Map Chamber as a Slytherin
Find the Map Chamber as a Ravenclaw
Find the Map Chamber as a Gryffindor
Spend all Talent Points
Reach Level 40
Complete all collections
Win the House Cup
Complete Poppy Sweeting's relationship line
Breed every type of beast
Complete Natsai Onai's relationship line
Upgrade a piece of gear 3 times
Discover all cairn dungeons
Complete all side quests
Rescue the phoenix
Complete all Merlin Trials
Stun 10 different enemies using a Mandrake
Reach the highest point in the castle, the Headmaster's upper study
Grow every type of plant
Use Flipendo ten times – to tip one cow or several
Complete Sebastian Sallow's relationship line
Brew every type of potion
Defeat Ranrok
Subdue the Lord of the Shore
View all Pensieve memories
Wield a Deathly Hallow
Beat Imelda's time in all broom races
Learn all spells
Use Ancient Magic on every enemy in the game
Defeat enemies in all battle arenas
Save a dragon
Upgrade a piece of gear
Defeat a total of fifty enemies using Petrificus Totalus
Find all Demiguise statues
Unlock all Floo Flames
Meet Charles Rookwood in the Map Chamber
Spend 5 Talent Points
Find the Map Chamber as a Hufflepuff
Reach a combo of 100
Visit Poidsear Coast
Follow butterflies to a treasure
Invoke Ancient Magic for the first time
Complete all tiers of a challenge
Survive the troll attack on Hogsmeade
Attend your first class
Complete the introduction and finish the Sorting Ceremony