So far, the only perps who tried to take a shot at Trump were a kid we still know nothing about for some reasons (usually, when the guy is Conservative we know every single details of his life in the following hours), and some NAFO-fella moron.
Threats to Trump's life have been numerous, but mostly noise by celebrities or randos with very courageous opinions but no fortitude to carry on with their threats.
With Trump back in office, it will be much harder to get to him during meetings and the Secret-Service will have to be on alert 24/7. Contrary to what the situation was during the 2024 campaign, be it for Trump of RFK Jr, when the security wasn't provided at an acceptable level to either a presidential candidate and a former president (who also happened to be a running candidate).
Personally, I don't see a foreign power doing it, especially with Vance as VP, unless they manage to get both POTUS and VP.
A foreign country would be writing and signing its own death warrant and certificate.
China? It isn't interested in going after Trump himself, in the end he is just a man, and just one man. Sure there aren't many like him or even anybody able to efficiently replace him, but what China aims for is effects on the long term to ultimately install and consolidate their supremacy. You don't achieve that by removing one guy.
Economic, commercial, technological wars are the things China relies on. And, recently, involuntary and indirect "biological warfare", as one could argue countries caused more damage to their economy, their population, their institutions and their population's trust in their own institutions than the virus itself.