The answer is that the US has a very fixed two party system, with free elections within each party to determine the nominee. Trump defeated the more traditional conservatives in the primary election in 2016. No elected president has been seriously challenged for renomination by his party, so the next opportunity for a traditional conservative is in 2024. In all fairness, it seems the conservative platform of small government and a muscular foreign policy seems somewhat out of favor at the moment.
In the election persons who dislike Trump, or Biden, have few choices as the American system makes it almost impossible for a “third party” to win (this happened only once, in 1860 when both parties fragmented, and the election triggered a civil war). Those unhappy with the presidential candidates can elect congressional candidate more to their choosing, and unlike most democracies, the American legislature is totally independent of, and in many ways more powerful, than the executive, and has a long tradition of annoying the elected chief executive.