Others have said that as well, but other than one country invading another--there are no significant similarities. What should be more concerning is how Biden has escalated the rhetoric until now he's pushing a goal of winning the war against Russia.
Realistically, though, comparing Russia's invasion of Ukraine to Germany's invasion of Poland is like claiming every time a luxury liner leaves port--it's the saga of the Titanic all over again. There's a good reason why we typically reject comparisons to Hitler and Nazis--and that's because they're over the top. The situation that led up to Hitler's invasion of Poland isn't even slightly similar to Russia's invasion of Ukraine. Hitler had a power agenda--Putin is responding to a failed Minsk II.
We are now in a proxy war against Russia, complements of the Biden and Obama Administrations.
It could very easily escalate--but not in the way you're thinking. There has never been an indication that Putin wanted to take all of Ukraine. It's all a lot of fearmongering. Deadly fearmongering.
It's very easy for all of us to take the superior position that might makes right so let's blow Russia off the map. But, we're poking a bear that has 10,000 nuclear weapons.
If the US would stop arming Ukraine, Russia would probably annex (with those resident's begging and leading for Russia to do so...) the narrow eastern strip of Ukraine and that's it. It's no big deal if Russia annexes that strip because the Ukrainian military and Neo-fascists have been slaughtering the pro-Russians citizens who live there for more than 8 years now. If we insist that Ukraine retains that strip, we are in effect insisting that those people die. 14,000 have died so far in that small region since 2014. Unless that area can be split off Ukraine, the same thing will continue until they're all dead.
What Putin is doing is wrong, but what Biden is doing is wrong on a much, MUCH more dangerous scale.
Be very careful what you wish for, and keep in mind that most luxury liners that leave the port will never be dashed on the rocks.