Layer styles are applied last in Ae’s render order (after masks, effects, and transformations, when native motion blur is rendered), so you won’t get the result you’re looking for from a layer style without precomping.
If you can’t use the native text stroke, you could avoid precomping by rolling your own Stroke effect, because effects are rendered before transforms. Stack up these built-in effects:
Minimax (to expand the layer’s boundaries, set to ‘Maximum’ and ‘Alpha and Color’)
Fill (to fill in the entire text area, set the color you want the stroke to be)
CC Composite (set to ‘In front,’ to comp the original layer source back on top of the expanded and filled text)