You need to download the essentials spawn plugin separate to essentials X I had this problem a few months ago when I started my server

welp, i suggest using EasySetSpawn plugin, since essentialsX dosen't come up with one(as far as i know). Correct me if I'm wrong

I would suggest command blocks:
first block (repeating command block):
/tp @e[tag=!spawned] where to spawn

second block (chain command block):
/scoreboard players tag @e[tag=!spawned] add spawned

however, this is a one time spawn, other times the player joins they will not be teleported