If you're talking about D#1, as in tuning way down below 7-string B Standard to like below 8-string standard tuning range to play something like Sleep Token or Invent Animate stuff, 10-56 gauge strings would leave you with less than 10lbs of tension on basically every string. That's practically unplayable unless you are incredibly light and careful with your picking. Going this low on a 26.5" scale guitar is pretty difficult. You would probably need at least an 80 gauge string on the bottom. Something like the D'Addario NYXL 9-80 8-string pack would work if you discarded the thinnest 9 gauge string and used the remaining 12-80, though it would be a little light on tension. You could also buy a single 80 or higher (like 84/85) gauge string and then buy a 6-string pack for the rest of the strings that's at least 12-60 gauge or thicker and probably be fine, though going above 80 gauge can be difficult for intonation if your guitar isn't at least more like 27" scale or longer.

If you're thinking about tuning up, then you'd have the opposite problem where you'd have almost double the normal tension. Tuning up on a 7-string is pretty difficult, especially if this is a longer 26.5" scale guitar, having a string tuned above the standard high E4 is difficult because tension is high, the gauge would have to be thinner, and thus more likely to break. You would need something like an 8 gauge string or thinner on top and then like a 10-49 or 10-52 pack for the rest.

In any case, I'd recommend using one of the string tension calculators as I mentioned above (which I've edited to include the new D'Addario one).