Like LesBrown said, lots of other threads on this topic. Not sure about your budget, but some options:
Option 1: 4 x outboard preamps via Line In (Lots of good new and used options, maybe around 1K up to the sky is the limit). This gives you six inputs and lots of really good drum kit recordings are done with six or less e.g. Glynn Jones variants etc.
Option 2: Add ADAT with 8 preamps e.g. Focusrite, Audient and some others make really nice units (New and used maybe around 500 and up). Now a total of 10 pre inputs, enough to cover the drums and plus four line in via DI e.g. keys, guitar, bass etc. for a total of 14 channels.
Option 3: Move up to Apollo x8p and sell the x6. (Guessing around 2K delta). Gives you 8 Unison inputs.
I think Option 2 is probably the most efficient balance of price and performance. I used a Focusrite Clarett+ Octo via ADAT for a while, then just ended up selling and picking up an x8 and some outboard pre's. Probably some other options as well.