Buying a used machine. Reinstall?

Hi together,

I'm offered a used system (specs below) running 10.12.6.

I wonder if I should do a reinstall to get rid of whatever might be lurking in the depths of the drive (who knows?). I have no prior experience doing the whole procedure. The other question is whether it would be hard to transfer the running system to me (different Apple ID).

Any ideas? Thx for helping!

Specs:

Intel Core i7-4790k

MB Gigabyte GA-H97M-D3H

16 GB RAM Crucial Ballistics

2,12 TB Fusion Drive

EVGA GTX GeForce 950 SC 2GB

AeroCool Case

for € 690,-