Hi Ava,
For bringing out the grain there's various oil based products, and grain fillers that will do the trick nicely.
The easiest to use would be Danish oil, it's a blend of tung oil and varnish and leaves a satin sheen rather than gloss. The benefit of Danish is that it's relatively quick drying, normally within 24 hours (further coats may be added earlier, check the tin for times).
To apply it just use an old but clean rag, you would generally leave it for a short time (again the tin will give you specifics, different brands will have slightly different formulations) then wipe off the excess. Usually about 3 coats is fine but as mentioned in my previous reply, sanding gently with a high grit sandpaper between coats generally gives the best finish. Sanding is definitely a recurring theme when it comes to wood!
Although it has varnish in its mix it doesn't provide the thicker buildup for protecting the wood as much as an actual varnish would, so it can benefit from a coat or three of clear satin finish over the top once fully dry. With sanding in between of course lol.
Couple of quick final points:
It does slightly darken the wood, you can try in an inconspicuous spot first to see exactly for yourself.
It does require good ventilation and a mask.
And finally the very important part. The organic compounds in Danish oil can cause dry rags that have been used to apply it or wipe off the excess to self ignite. Never personally had this happen, but there is the risk of a bin fire or worse. Sounds bad but it's easily prevented. When finished always rinse out the rags in water before they go in the bin.
Hope that helps!
Stuart