Trump obviously didn't work some magic with his perfect, beautiful policies, but if you wonder why anyone might actually credit him with a good pre-covid economy, it's because the economy was actually at a genuinely low level of unemployment, the kind of unemployment rate plausibly associated with "full unemployment," something rarely experienced in the country since economists declared war on inflation and decided to never let the unemployment rate drop that low ever again.
4.7% unemployment rate in November, 2016, 3.5% in February, 2020. The difference between "I can find a job" and "I can find a job and get a raise."