I usually work with Alexa footage that's shot at one of three presets (3200K, 4300K, 5600K). Sage’s LUTs work really well, but getting the best match requires white balancing both the S1 and Alexa to neutral white before converting. Alexa white balance presets are not neutral–they're orange/green.
I wanted equivalent white balance presets I could use (5600k, 4300K, 3200K) with the S1, where I could shoot V Log, apply Sage's LUT, and get a ballpark match to Alexa presets–even if it might be a little less precise than doing this the right way.
I lit a white card with a Luxli RGBW light at 3200K, 4300K, and 5600K and then shot Alexa footage shot at 3200K, 4300K, and 5600K presets.
Then I shot the same with an S1 and and applied Sage’s Log C conversion LUT. I adjusted the white balance settings manually until I got a good match.
I've only tried out the 5600K preset so far in the field but it matches pretty well.
K1: 5600K A: 6 G: 9 (should be G: 10, but it doesn't go that far) – apply Daylight Log C conversion
K2: 4300K A: 6 G: 6 – apply 4200K Log C conversion
K3: 3200K: A7: G: 4 – apply Tungsten Log C conversion
Beyond that, a bit of extra noise and a bit of unsharp mask after downscaling S1 4k to Alexa 2k/3.2k (amount 24, radius 3) also helps make S1 footage look more like Alexa footage.
If this isn’t for you, ignore this post. It's not as precise as doing things the right way but for my needs is much more convenient.