Simple:
* The magnolias in the garden were in full bloom.
* The magnolias are a beautiful and fragrant flower.
Descriptive:
* The magnolias stood tall and proud, their creamy white blossoms filling the air with a sweet, intoxicating scent.
* The magnolias were a symbol of spring, their delicate petals unfurling with the warmth of the sun.
Figurative:
* Her smile was as bright and beautiful as a magnolia in full bloom.
* The magnolias were a reminder of the fleeting beauty of life.
With specific information:
* Southern magnolias are known for their large, fragrant flowers.
* The magnolias in our garden are a hybrid variety with pink petals.
You can also use "magnolia" as an adjective:
* The magnolia tree stood tall and graceful.
* The magnolia scent filled the air with a sweet fragrance.
The best way to use "magnolias" in a sentence depends on the context and what you want to convey.