A regency-era Ravenloft setting is something I’ve had bubbling away in the back of my mind for many years and have copious notes on. That time period is much better suited to Ravenloft’s gothic vibes than conventional d&d approximate-renaissance anyway, and many Ravenloft domains are straight from English ghost stories. One day I’ll write it up, once I’ve worked out how to do firearms properly maybe!
One thing default D&D doesn’t do well, though, is property. Many d&d characters own only what they carry, and live in inns or tents. Who you are, who your people are, where you live, whether you own land, or rent, or run a business, and how well and diligently you do any of those things - that’s all the absolute crux of most of Austen, but D&D in its standard form just doesn’t touch it.
For starters, I was going to introduce two new skill proficiencies. Society (usually Cha but sometimes Int) represents knowing etiquette and table manners, dancing fashionably and well, having good dress sense, recognising the names of prominent people, having heard the gossip, etc. Manager (Int) is about balancing a budget, knowing the law, understanding politics, being able to run a successful business or estate, etc etc.