Can you play as Bruce Wayne in LEGO Batman: Legacy of the Dark Knight?
Yes — young Bruce is playable throughout the Prologue (Wayne Manor, Falcone Confrontation, League of Shadows training).
The Prologue puts you in control of young Bruce across seven missions — Wayne Manor Grounds, the Falcone Confrontation outside the Iceberg Lounge, the climb up Nanda Parbat and combat / stealth / gadget training with the League of Shadows, ending with the temple infiltration vs Ra's al Ghul. After the Prologue you play as Batman. Bruce Wayne also appears in story cutscenes (e.g. the Bruce / Selina 'Date Knight' in Chapter 3) but isn't separately swappable in free roam.