I visited the Capitol Bldg and WH in 2017 after Trump took office. You had to go through a LOT of security to get in, including making a reservation on-line the day before.
Even more security than the Clinton Presidential Library in Little Rock.
So nobody with any common sense would think it was OK to just walk in.
You would if you had never been there before, a cop waved you in walked beside you and casually chatted with you as you went.