Grain and varnish- sanding

[Tigercubrider]

got part way through sanding a wooden conservatory- hardwood to be stained/ varnished

So far I have used an orbital sander along with a belt.
I aim to stain it a little, then use a couple of coats of varnish
I'd like to show off the grain if possible

So having bot most of the old coating offf with the mechanical sanders, how much would I need to sand along the grain to allow the grain to come through the varnish?

Thanks