This console command assimilates the province with the specified ID. When a province is assimilated, ownership is switched over (to the assimilating country), it is cored, and both its culture and religion are changed to that of the assimilating country. If you do not specify a country tag as an argument, the country you are playing as will assimilate, otherwise, the country with the specified tag will assimilate the province.
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228 is Beira's province ID. This command would make your country assimilate Beira.
assimilate 230 LIT
This command would make Lithuania (country tag LIT) assimilate Algarve (province ID 230).