Carry the detail all the way around the house. Design every side of a house as if it is the front.

IMO you have a busy front of house already so leave it alone or at least show us where you were planning this extra trim

Thank you so much the ideas. The entire house will be redone in hardie so unfortuneltby all the dentil crown will come off too. I’m having a hard time finding nice azek or pvc crown

These guys Royal Building Products have some.

You might also look at this material: https://fypon.com/

It holds paint very well.

Fypon looks great. Is there anything I don’t have to paint azek or arctic white

Azek trim needs to be painted from I recall.

I always use Restoration millwork by CertainTeed, they have a large selection of exterior products, trim, sheet goods, etc.

Why does the cornice trim need to be removed?

https://www.vintagewoodworks.com/crownmoulding.html

Long story short. Some of the boards under the dentil mouldings have been damaged from water and lack of painting

Are the Azek and other cellular PVC brand moldings not large enough?

I agree about carrying any design detail all the way around the house and not just stuck onto the front facade. These days most of these architectural details are "stuck on" but if you carry it all the way around the house then it looks like an intentional design plan. If you just stick them on the front only, then it really looks like fake stuck on trim.

We built last year and made sure to add all the same trim details all the way around the house.