Yes, but it's not the best server for that because single core performance is pretty bad on those old Opterons.
I used to host a Minecraft server on a PowerEdge 2950 with 2x Xeon E5420 and 32gb of ram. It was able to run 50 players on a server with about 50 plugins without any problems, though that was back in 2013.
Best Opteron for that server has a bit slower single core performance than the E5420 but it has 2 more cores. What CPUs the one on ebay have?