They'd also need to bribe lawmakers to add an exception to the foreign agents law that allows the Chinese to donate to people running for US office without needing to register as foreign agents.
There are other ways to donate to nonpolitician social media owners who then donate to politicians or support through their algorithm Like allow an individual who owns a big media platform to have the first fully foreign owned auto factory in China. In Musk's case it was before the Twitter purchase so not saying that's what happened there, just that that kind of thing is an avenue.