If you were discussing the British Conservative Party or the Canadian Conservative Party, I would completely agree with you on that. The American Republican Party, no, not at all. In fact, rather than moderate their positions to appeal to a larger and more diverse percentage of Americans, they just want to make it harder for those outside of their base to vote. You take a moderate, center-right Republican like Charlie Baker, governor of Mass, if the GOP base nominated him in 2024, he would win in a landslide, and probably have Eisenhower approval ratings the entire time he was in office. However, they would never in a million years nominate a moderate Republican like him. They would rather continue to try to win with a minority of American votes, and this true true across the board, than nominate candidates that would appeal to the majority of Americans - which would not be that difficult considering it is a center to center right country.
I mean hell, in 2012, had Romney been able to run as the pragmatic center-right Romney that was governor of Mass, he would have easily won, but instead the base demanded him to run as "severely conservative", and he lost (though he did have a higher percentage of the vote than what Trump won with in 2012).