Will dual channel mode work with 2 memory modules and soldered memory?

Question

laptops

I have 1 stick of RAM for 4 gigabytes in my laptop and another 4 gigabytes are soldered on the board. I plan to replace the 4 gigabyte memory module with 2 by 8, but then the question is brewing: will the dual channel work, and if so, will it work normally?
Notebook model Lenovo IdeaPad s340-15api.

Answer 1

https://www.lenovo.com/ru/ru/laptops/ideapad/ideap...

RAM
Up to 12GB DDR4 (4GB soldered + 1x 8GB SO-DIMM slot )

I did not find information on memory compatibility, and the dual-channel mode has very sensitive requirements, something is a little wrong, it does not start.
and definitely not , if there are different sizes of RAM (and you get 4 + 8, or even if I looked at the wrong configuration, it turns out 2 + 2 + 8 + 8, this mode will still not start, motherboards on which partial the work of the multi-channel mode can probably be counted on the fingers, I have not seen it)