I contacted MSI about my then new laptop back in 2015. I wanted to add an additional two SSDs (it had an empty m.2 slot and a spinning 2.5" and the OS on a single m.2 SSD).
The problem was that to remove the bottom, I'd have to destroy a warranty void sticker.
I emailed them and they replied in no time at all confirming that removing the sticker to perform the upgrade was not an issue and would not affect my warranty.
I'm in the UK.
It is my understanding that here in Europe, the same rules will be honoured with respect to warranty void stickers so long as you don't cause damage while voiding the sticker to perform whatever it is you're doing.