Not interested in wearing a corset?
Not wanting to do empire waistlines?
Consider the informal dress styles of the 18th century
Women's waistcoats were often quilted, bot not always
Here are some historical and reproduction inspirations.
V&A 1700-29 494-1902
V&A 1745 T.87-1978
Vintage Textiles C.1770
Vintage Textiles 1800-30 (old fashioned)
Sharon Ann Burnston has a pattern online from an 1740-80 quilted waistcoat
Mara Riley's Time-line of Women's Jackets briefly covers waistcoats of the 18th century.
Two Nerdy History Girls on quilted waistcoats. the ones shown are reproductions
Diary of a Mantua Maker made a reproduction
Costumes, Cats, and the 18th century posted photos from the Power of Fashion exhibit at Nordiska Museet in Stockholm, which include a quilted waistcoat that was not assembled, great for etting a look at the shape of the pattern pieces.
Another option is the Bedgown
Manchester 1760-80 1972.110 Detail of fabric
Shortgowns are another option
There are other informal robe styles available as well.
A Banyan is also an option. The V&A has a lovely example. T.92-2003
If you do a websearch for Banyan, most of the examples you will find are for men, not women, and this pair was likely worn over pocket hoops, given it's shape.
Robe Volante 1720 French from Kyoto Costume Institute AC9184 95-1-2
Another that was auctioned at Christies
Painting titled The Declaration of Love by Jean-François de Troy 1731
Isis made one and her research is fairly good.
Please remember that these styles listed hear may have been worn over stays in period, they are just a few examples of what a modern woman may be able to wear without stays.