Yes, you'll have two choices (or three if they bring out another SKU with more storage).
1) Buy an external USB HDD/SSD and keep copying PS5 games backwards and forwards to the internal as and when you want to play them. (PS4 games will run from an external drive.)
2) Buy an NVMe card which can be plugged into the console itself. But you'll need to get one that Sony have certified for the PS5 (needs minimum transfer speed of 7GB/sec).
1) Buy an external USB HDD/SSD and keep copying PS5 games backwards and forwards to the internal as and when you want to play them. (PS4 games will run from an external drive.)
2) Buy an NVMe card which can be plugged into the console itself. But you'll need to get one that Sony have certified for the PS5 (needs minimum transfer speed of 7GB/sec).