You can buy the Galaxy S23 models with a fair bit of internal storage, up to 1TB for the Galaxy S23 Ultra, but that's all you're getting. There's no microSD card slot so you can't externally upgrade the storage. They only other option is to pay for a cloud storage service but that can end up being very costly.
The alternative is to invest in a USB-C flash drive. It connects to your device's USB-C port and provides you with external storage. Samsung makes a great USB-C flash drive that's available with up to 256GB of storage. It offers 400 MB/s read speeds and also happens to be waterproof.
Buy Samsung's USB-C flash drive from Amazon for $16.99. It's at a 26% discount today so go ahead and buy one, particularly if you've pre-ordered a Galaxy S23, so that you always have the peace of mind you're not going to run out of storage.