Optical sizes
Louvette Banner has ultra thin hairlines and tighter spacing for usage above 96pt. Louvette Display is the next size which is ideal down to 72pt, with Deck down to 36pt, and Louvette Text's thicker hairlines and generous spacing allow it to hold up for large text sizes around 14pt. In addition to the hairlines and spacing changing for the intended size range, the descender lengths change as well. So your largest text can be tightly stacked for maximum impact without the descedenders crashing into the line below, and your smaller text can have ample leading with long descenders to elegantly fill the space. If you want to override the defaults, alternate descender lengths are also available via OpenType Stylistic Sets, SS03 for Short Descenders and SS04 for Long Descenders (see below).
For more information about optical sizes in typeface design, I highly recommend this book: Size-specific adjustments to type designs by Tim Ahrens and Shoko Mugikura. The red and blue image above is a nod to their wonderfully insightful book.
Descender length
Louvette Banner includes shorted descenders by default allowing for extra tight leading, while Louvette Text has longer descenders by default to gracefully fill settings with more leading. The longer ones are available as stylistic alternates and grouped in Stylistic Set 03 (SS03), while the extra short descenders are grouped in Stylistic Set 04 (SS04). Louvette’s variable fonts include a descender axis (ytde) so you can change the descenders to any arbitrary length in between long and short as needed. This is particularly handy when you have a collision in a particular setting and don't want to change overall leading for other settings, so you can just change the descender of a single glyph and leave the rest alone.
Hairlines
With the Louvette variable fonts you can adjust the hairline axis (yopq) independently. The is particularly useful if you have light text on a dark background and need to thicken the hairlines to avoid ink from filling in, or on screen for “dark mode” settings.