Is there a standard cell library which uses the 3v3 fets? I know the OSU library does but it doesn't seem to have lib files for the cells. Alternatively how can I generate lib files? Is this something that magic can do? I am not familiar with the liberty files at all really

Generating liberty timing files for standard cells is a non-trivial task. There should be liberty files for the OSU set, but I'm not sure what the status is, whether they are publicly available or not. You can ask @James Stine. . .

@Tom When new to characterisation, i recomend the compact opensource lctime (basically it is a simple Python package for characterizing CMOS stdcells). It is based on ngspice and dosn't require opensource TCAD-tools (e.g. gmsh masher and devsim or sandias charon) https://codeberg.org/librecell/lctime/src/branch/master/lctime/characterization

I have ported my standard cell library generator to GF180, so you could try to generate 3v3 fet cells with it if there aren't any available. https://github.com/thesourcerer8/StdCellLib/