Yes, as Raul points out, phrases work on LPB - which are whole number ratios.
This works for playing a phrase in double tempo, dotted/triplet (1/3, 2/3, 3/1, 3/2 - and so on) - but you can’t set the phrase to play with a separate BPM. So, no 126 bpm slowly drifting away from 128 bpm (or whatever the tempo is in Steve Reichs Piano Phase :))
However…
The tool would use delays to create an exact transformation of the speed of the music, allowing you to make really slight adjustments to a track’s playing speed which would be particularly useful for combining tracks from different sources or different recording “takes”.
Yes, I believe you gentlemen are looking for the Flexible Pattern Resizer:
https://forum.renoise.com/t/new-tool-2-8-3-0-flexible-pattern-resizer/30664
Works on a pattern basis…so if you need to resize just a part of a pattern, use the built-in “split and join pattern” feature.
Split: Pattern Editor > rightclick > Pattern > Split
Join: Pattern Sequence > rightclick > Organize > Join
If you want to record multiple takes and select the best one:
http://www.renoise.com/tools/auto-clone-patterns ← essential tool if you ask me, allows you to “endlessly record” on top of a looped pattern sequence
http://www.renoise.com/tools/noodletrap/ ← allows you to record into phrases instead of pattern.