When a Legendary enemy is defeated in Fallout 4 they "drop" a Legendary item. These items are randomly generated but the "level" of items (ie. usefulness, value) appear to increase as the player progresses through the game.
Travelling East or South early in the game exposes the player to higher level enemies so it is possible to engage with enemies many levels above the player.
If a level 10 player defeats a level 30 Legendary enemy would they get the same "level" Legendary item (ie. usefulness, value) as a level 30 player defeating a level 30 enemy?