If you needed to apply for a Vietnam visa renewal because your visa is about to expire but you wanted to extend your stay, you should go to the Vietnam Immigration Office. Thankfully, there are several offices across the country, so there’s no reason to travel far for your visa renewal. Aside from the Vietnam Immigration Office in Hanoi and Ho Chi Minh City, you will find the immigration office in Da Nang and other major cities in Vietnam.
https://www.vietnamimmigration.org/full-list-of-the-immigration-offices-in-vietnam/
To find out if there is an immigration office where you reside, just go to the website of the Vietnam Immigration Office. Here, you will find a list of all the Vietnam Immigration Offices all over Vietnam, along with their addresses and contact numbers. Although the main requirement for applying for a visa renewal is the passport, Vietnam Immigration might require you to submit several other requirements as well. So to be sure, it is best to call them in advance and inquire.
https://www.vietnamimmigration.org/what-document-required-for-vietnam-visa-renewal/
