Well – the obvious way would be to ask your realtor, or ask the listing agent.
I’m not sure if you variances are recorded with county recorder. If they are you could take the parcel number, APN, (on the listing or on redfin), plug it into the property tax database. If the land is held by an entity with a unique enough name, you might be able to plug that into the county recorders database.
If (and only if) variances are recorded with the county recorder – you’d be able to see if there’s a doc. You can order the doc for a few bucks or go down to the county building to look it up for free.
Like I said- asking the listing agent is the easiest way.