helo friends

Had my first self built pc for a few years now and wanted to add a second gen 3 nvme to it, because i saw a good black friday deal. But of course my motherboard does not have a second m.2 slot.

After looking around a little i read that adapters exist but also appearently using your second 16x pcie slot can downgrade your graphics card to running on 8x when you do so.

And I’m curious if you guys can tell me if my motherboard (https://de.msi.com/Motherboard/B450-TOMAHAWK-MAX/Specification) is fine to use with a 16x pcie adapter for nvme or not.
Really don’t want my graphics card to run slower in exchange for 2tb of extra space for games.

Or should I maybe handle it another way entirely?

Cheers and thanks in advance!