If you see any void stickers on the case, then no, most likely not.
Paradoxically, the same manufacturers had often allowed self-upgrade on their laptops, in my experience - though that was often limited to memory, HDD/SSD, wi-fi module, and in older times, CD/DVD burner, without voiding the warranty on the rest of the system except for certain caveats, like what USAFRet said.
Not sure what system you have, but may want to swap for a different power supply. Take pictures of how it looks, then if you need warranty for anything not related to the upgrade, put it back like it was. But realistically if you have clean power and all the parts can stay cool you probably won’t have any issues.
If you see any void stickers on the case, then no, most likely not.
Paradoxically, the same manufacturers had often allowed self-upgrade on their laptops, in my experience - though that was often limited to memory, HDD/SSD, wi-fi module, and in older times, CD/DVD burner, without voiding the warranty on the rest of the system except for certain caveats, like what USAFRet said.