Space for the things you keep.
An SSD is the drive that stores your apps, documents and photos. Its capacity is different from memory.
256GB, 512GB or 1TB?
256GB can suit a light cloud-based workflow, but leaves less room for photos and larger apps. 512GB is a practical general starting point. 1TB is useful for sizeable local media or game libraries.
Count your files
Look at the storage you use now, add the applications you need, and leave spare space. Your operating system uses part of the advertised capacity.
Cloud and external drives
Cloud storage can reduce local needs, but may require a subscription and internet access. External drives are useful for archives; neither option replaces a considered backup plan.
This is buying guidance, not a hands-on product review. Verify the exact configuration and application requirements before purchase.