Soul fragment gavel of aribtor

im using a gavel of the first arbitor. saw a way to highlight the border with weak auras. the guy on youtube vid said plater can be used to make the nameplate of chosen npc bigger. how do i do this? also saw someone say you can use elvui nameplate section to control size of nameplates. followed those instructions but it doesnt work. saw it was an earlier version than one im using now. for making soul fragment nameplate bigger.

ElvUI you just do it with a style filter and match the unitid then style it how you want.