Question Question regarding upgradability of LG gram 2021 16"

It comes with two DIMM slots. One is soldered (8gb) and the other removable and upgradeable.
it's never recommended to mix packaged sets of RAM due to possible lack of total compatibility even between the exact same make\model sticks.

but, considering that this system has a supposed "soldered" in place module;
i would check the laptop manufacturer's product support page for a memory QVL list
and get one with the closest rated specs to what is already included.

if your plan was to try and add a faster module with better timings, ect;
that would not be possible because the system will default to the lowest module's available speeds.
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