If you want to replay the Merlin Trials in 'Hogwarts Legacy', here's the practical picture from my playtime: some of the Trials and
Challenge-type activities are replayable through the
Game's activity markers, while story-locked trial events behave more like one-time missions unless you load a save or
restart the game. In other words, your ability to replay depends on whether the Trial is flagged as an activity/challenge in the map or as a key story beat.
When I wanted to run a Trial again, my first move was always to check the Activity/Challenges tab in the menu and then the world map for a Trial icon. If it shows up as an active activity, you can usually walk up and redo it on the spot. For Trials that are tied directly to the narrative, I kept a manual save just before the trigger—this made it easy to replay the sequence without affecting my broader progress. If you don’t have a save, the other route is using a New Game+ (if available on your platform and installed) to replay the main story while keeping some progression, which lets you re-experience story Trials with higher-level freedom.
Pro tip from my replays: always make a quick manual save before a Trial, and check patch notes—developers sometimes add replay options or Challenge menus in post-launch updates. I found replaying some Trials great for practicing combat combos and trying different builds, so I often used them like mini training runs; it kept the game feeling fresh and rewarding.