There's: U+3000, ideographic space. It's conceptually fitting, with sentence separation being a good fit for "idea separation".
edit: well I tried to give an example, but hn seems to replace it with regular space. Here's a copy paste version: https://unicode-explorer.com/c/3000
The extended horizontal size is the only goal here. The dimensions for a sinoform is still related to pt size, so the relative spacing, compared to chr(32), at the same pt size, is reasonably larger.
But...the vertical dimensions don't scale so well, at least in my browser. It causes a slight downward shift.
You’d perhaps be better off using U+2002 EN SPACE (or the canonically equivalent U+2000 EN QUAD).
From what I recall, the size of a typical interword space is ⅓ of an em, and traditionally a bit more than this is inserted between sentences (but less than ⅔ of an em). The period itself introduces a fair amount of negative space, and only a skosh more is needed if any.
Belying the name somewhat, I believe U+3000 is specifically meant for use with Sinoform logographs, having the size of a (fullwidth character) cell, and so it makes little sense in other contexts.