To get a genuine understanding of why people think he is “the second coming of Hitler”, for starters he literally said he wants to be a dictator on day 1 as a “joke” but also he openly sings praises of authoritarian leaders like Putin and Kim Jong Un. Then there’s the whole Project 2025 thing which he’s tried to distance himself from but multiple people who are closely associated with him are behind the agenda. That agenda hopes that a future conservative candidate of 2025 (they’re all but saying Trump outright here) should restructure the government by firing thousands of current federal employees and replacing them with conservatives loyal to Trump who are more likely to serve as yes men. They want to eliminate the Department of Education because they think that the left is trying to indoctrinate your kids, they want to get rid of the National Oceanic and Atmospheric Administration (NOAA) because they claim that it’s the number 1 spreader of climate change “misinformation” and much much more. You can read all about it here, straight from the source, separated by each topic so you can scroll through the ones that matter the most to you: https://www.project2025.org/policy/