Question about ASUS ROG Strix Z690-E Gaming Wifi

Depends on what you mean by SSD slots, broadly speaking there are two different ones. The SATA SSDs (e.g. Samsung 870 EVO (1000 GB, 2.5")) and M.2 SSDs (Samsung 980 Pro (2000 GB, M.2 2280).).

This mainboard supports 6x SATA and 3x M.2 SSDs (or these connections are available).