Depends on the style of home as to what would be appropriate. Chunky moldings are wrong for both a Colonial with 8' ceilings or MCM home with 12' ceilings.

Here is an article that may help.

https://www.houzz.com/magazine/how-to-size-interior-trim-for-a-finished-look-stsetivw-vs~2934773

With 8' ceilings, crown molding height is usually 3 1/2” – 4 1/2” and Baseboard is 3
1/4” with 2 1/4” – 2 1/2” Casing

GN Builders, you have helped me in the past. Hoping you can help me out here too. For a 10 ft ceiling, what should be the optimal height of baseboard, crown molding and casings? Are the window casings typically the same width as the door casings?

AXP, you can go with 5 1/4-7" wide base, some people who like high trim use 8-9".

Yes, the doors and windows usually get matching casing.

Good luck