He wants to follow through with these plans to appease his cult but he cannot (at least not militarily) as the blowback would effectively end his regime and possibly the US as a whole.
So his plan has been to topple Canada's economy through economic pressure but that has been backfiring too. Canada may only have a tiny fraction of the population the US has but we do a huge amount of trade with them, have a lot of resources they require, host a lot of their manufacturing, and we hold a lot of their treasury bonds and national debt. There is no way for the US to have a trade war with Canada without walking away with catastrophic losses across numerous industries and a highly devalued US dollar.
We have already seen that, when under real pressure, Trump will fold. Most notably, he's done it with Canada under Carney and with China. So for now these threats are just hot air to appease his base and to act as a distraction while he plunders the country's coffers. But we need to treat him and his threats seriously as we would any other threat to sovereignty because one day these won't be just threats. The US is lead by a senile fascist tyrant whose mental health degrades by the day; he should be treated with extreme caution at all times.