That’s only true for the Senate. 2 Senators for each state, regardless of population, 6 year term.America is not a centralised state, its federal and designed to ensure that no single party, belief or state can win by a majority of votes and thus seize control of the federal state. The European union operates a similar system, otherwise the big countries would have total control of the federal state and the smaller states would be without power or a democratic mandate.
For the President, the numbers of electoral college representatives vary with population. Texas has 38, Alaska has 3. 4 year term.
For the House, the numbers of Congressmen/women vary with population. Texas has 36, Alaska has one. 2 year term.
If the populous states all happened to swing the same way, then they would gain control of the Presidency and House easily. The Senate however could potentially be in opposition. In actuality though, some of the more populous states are in general opposition to each other. California is strongly Communist, while Texas is strongly Utopian