No, HCS can’t prioritize cells of the same layer. If signal strength of a cell is better than its LAYERTHR it will be ranked better than all of the higher layer cells, not the same layer. And if SS is worse than LAYERTHR then it will be ranked according to basic ranking and Layers won’t be considered.
In your case you can put this cell into Layer-3 and then every MS with SS better than -90 will be assigned to a Layer-2 cell.
Secondly, why don’t you use other offloading techniques rather? Make CLS more aggressive, increase the value of AWOFFSET, give negative CRO etc.