This claim is accurate. Trump recently threatened 100% tariffs against BRICS countries if they moved to replace the US dollar with another currency as the primary currency for international trade.
https://truthsocial.com/@realDonaldTrump/posts/113573130299319701
BRICS, which stands for Brazil, Russia, India, China, and South Africa, is a group of countries that have aligned in recent years with a shared goal of increasing their global power. The group, now including Egypt, Ethiopia, Iran, Saudi Arabia, and the United Arab Emirates (UAE), is aligned in the belief that the international economic and political system disproportionately favors Western economies, and neglects non-western, especially developing countries. BRICS countries have pushed for greater representation in international political and economic institutions, economic policies shifted towards BRICS states' interests and lessened reliance on the U.S. dollar on the international market. BRICS country leaders have often suggested a BRICS common currency as a way to lessen the dollar's influence, which is what Trump is referencing in his post.
https://www.cfr.org/backgrounder/what-brics-group-and-why-it-expanding#chapter-title-0-1
The idea of a BRICS common currency has been proposed, but there is by no means a meaningful strategy or plan to realize such a drastic shift. Many BRICS leaders have publicly supported moving away from the dollar, but there has not been a cohesive or clear message as to how this would be executed.
https://www.reuters.com/markets/currencies/what-is-brics-currency-could-one-be-adopted-2023-08-23/
Trump's threats seem to counteract other elements of his proposed policy. According to Michael Pettis, a senior fellow at the Carnegie Endowment for International Peace, increasing the global dominance of the US dollar contradicts Trump's aspirations to reduce the U.S. trade deficit. Trump's threats are indicative of "how confused the incoming administration is about the global trade and capital system."
https://finance.yahoo.com/news/trump-demands-commitment-brics-nations-182124427.html?guccounter=1&guce_referrer=aHR0cHM6Ly93d3cuZ29vZ2xlLmNvbS8&guce_referrer_sig=AQAAAI2qp1we8SOGLIgizv0PCxGwD9QnZHyvfa794VpKDNObgm71hsbUjKWclPk3pwBoQG4JwaAQ6z0LqrnPsq8FgJS9We7YRYtE-oNKYWLN9i8YP0BmEyWHLvkEkVY2188c3N9YHgy7YF3tT8ybWlMNASRnbJuUGcpIE9eVarJR5bOY