Yes, former President Donald Trump did say "he couldn't care less" in a few contexts, notably regarding political unity and other issues. For example, when asked by Fox News how he would make America "come back together," Trump replied, "I'll tell you something that's going to get me in trouble, but I couldn't care less," before going on to blame radicals on the left as the main problem and minimizing the concerns about division.
He also used the phrase in other situations, such as expressing indifference to automakers raising prices after tariffs were imposed, saying "No, I couldn't care less" regarding price increases.
Overall, the phrase "couldn't care less" came up explicitly in his statements, usually signaling strong dismissal or indifference about certain matters, including political unity and policy outcomes.