The CubeMX tool does offer the Atollic True Studio target for the code generator.
Respectively, the integration of the TouchGFX tool inside the CubeMX will also proceed to generate wizard generated code for this same target compiler.
However, at this time of writing, the final generated code does not appear to compile well as a group. This is being worked on by the ST developers.
If possible, consider to use IAR or SW4STM32 compilers for now. You will find full documentation on how to proceed with the IAR or SW4STM32 tools (with CubexMX & TouchGFX integration) to assist you to get started.
Hope this helps.
