LOL, are you serious? If you think top echelons of the US government, beginning with the President, don't push fringe stuff, conspiracy theories, you obviously aren't aware of what's going on, right now, post election.
Ignorant theories spouted by the President and a few top aides are not representative of the entire US government, and certainly aren't representative of other Western governments. The American scientific community, including Fauci, came out pretty strongly against the notion of a bioengineered virus, and the U.S. intelligence community followed suit:
The theory that COVID-19 originated in a lab in Wuhan has emerged as a highly contentious claim since the outbreak began.
www.forbes.com
Trump has made it very clear he doesn't trust the intelligence agencies, as to him they're all part of the nefarious deep state, so it's no surprise that he would ignore or contradict what they say. There were some who suggested the virus could have escaped from a lab. While this seems highly unlikely, this is more difficult to rule out unequivocally, simply based on the sequence of the virus.