Democracy (in the US) is the whole system, not just the president. Biden didn't achieve everything he promised because he was in contention with the senators and representatives that were also elected by the people; same for Trump. It's checks and balances, the president can't do everything he wants because he gets checked by Congress and the courts; Congress can't do everything they want because they get checked by the president and the courts. Trump is straining that right now but that's the soul of American democracy – one guy doesn't decide it all, they must cooperate with Congress.

We'll see the system turn against Trump after the November election, when democrats are expected to take the house and probably the senate back from Trump's party. That's democracy in action: people are extremely unhappy with how Trump is handling things, so they're punishing him by voting in representatives who promise to rein him in.