The Intel Core i7 2600K will be fast enough for most regular things, but it is quite power hungry, so not so great on your power bill. Also the Intel Quicksync in it is old and thus not very helpful for hardware transcoding videos in Jellyfin, meaning you would need to do it on the CPU, which is much slower.

24GB RAM is definitely sufficient for most things and the SSD storage as well, although you might want to add some redundancy to that at some point.

The Geforce is pretty useless for server tasks and the NVenc chip in it is also pretty old, so I would just remove it, or maybe ask the seller to remove it and sell separately.