Wash. Rev. Code § 66.44.350
Notwithstanding provisions of RCW 66.44.310, employees of businesses holding beer and/or wine restaurant; beer and/or wine private club; snack bar; spirits, beer, and wine restaurant; spirits, beer, and wine private club; catering; and sports entertainment facility licenses who are between eighteen and twenty-one years of age may take orders for, serve, and sell liquor in any part of the licensed premises except cocktail lounges, bars, or other areas classified by the Washington state liquor and cannabis board as off-limits to persons under twenty-one years of age: PROVIDED, That such employees may enter such restricted areas to perform work assignments including picking up liquor for service in other parts of the licensed premises, performing clean up work, setting up and arranging tables, delivering supplies, delivering messages, serving food, and seating patrons: PROVIDED FURTHER, That such employees remain in the areas off-limits to minors no longer than is necessary to carry out their aforementioned duties: PROVIDED FURTHER, That such employees are not be permitted [are not permitted] to perform activities or functions of a bartender.
RCW 66.44.350