Link to the museum page: http://natmus.dk/historisk-viden/temaer/modens-historie/1790-1840/bukser-og-jaket/
Evolution of the collar and lapels is especially apparent wen compared to the common style of 5-10 years prior, as seen on this American linen coat from the MET, accession # 1997.508 and a coat of similar cut worn by Granville-Leveson, 1st Earl Granville in England, both ca. 1815.
Collars and lapels sat very noticeably higher at that point. Look closely here and you can see that William Croghan, Sr. of Locust Grove near Louisville, KY was keeping up with evolving fashions when his portrait was painted in 1820 at the age of 68 by John Wesley Jarvis (Collection of Historic Locust Grove, Louisville, KY):