The last time China annexed an entire country would be in 1951, however China has been taking little bites out of its neighbors since then[1]. Moreover, there is little dispute that China desires to annex Taiwan, which is at this point a fully independent country and a functioning democracy.

China is building settlements and outposts outside its territory in a number of places including their western[2] and southern[3] borders and eastern outlying islands[4]. In 2020 China recently largely ended democratic self-determination in Hong Kong, which had otherwise been promised 25 more years of independence.

[1] https://en.wikipedia.org/wiki/Territorial_changes_of_the_Peo...

[2] https://www.cnbc.com/2022/05/25/china-is-building-a-bridge-o...

[3] https://foreignpolicy.com/2021/05/07/china-bhutan-border-vil...

[4] https://www.theguardian.com/world/2022/mar/21/china-has-full...