free patterns:

https://www.lacma.org/patternproject

http://www.uvm.edu/~hag/godey/fashion/di.html

https://www.antiquepatternlibrary.org/html/warm/F-PK001.htm

http://www.reenactor.ru/ARH/PDF/The_Cut.pdf

https://www.cuttersguide.com/galleries/pattern-guides-male/

http://victorianpatterns.pbworks.com/w/browse/#view=ViewFolder&param=Patterns



general resources:
https://vinceaddams.tumblr.com/post/186970565023/op-got-any-advice-on-finding-sources-for-18th-c
https://www.cuttersguide.com/
http://costumebase.org/en/index.html


list of paid patterns if you decide you'd rather go that route:
https://historicalsewing.com/patterns-for-well-dressed-19th-century-gentleman


basically Intense Faggotry: The Website but the links on this page of it are worth including:
https://costumes.org/2020/07/19/the-cutters-practical-guide-by-w-d-f-vincent/