Oh, I also keep an eye out for pieces that might not intentionally be Era specific, but have that classic Edwardian appearance. Like the dress Annette wears to the Conley Party, I'm pretty sure I got that from The Sims Resource. Sometimes just finding a dress that has the right shape, length, sleeves and adornment can work (especially when paired with long gloves or something!)
April on TSR makes a lot of beautiful dresses https://www.thesimsresource.com/artists/-April-/downloads/browse/category/sims4/skipsetitems/1
This was actually the dress Annette used: https://www.thesimsresource.com/downloads/details/category/sims4-clothing-female-teenadultelder-formal/title/aleysha--gown/id/1366073/