Can I run GPT-X3-150M on a Mac with 24 GB?

Yes

Its published weights (598 MB) fit in the 16.0 GB a Mac with 24 GB can use, with room for an unknown amount of context.

hf download AxiomicLabs/GPT-X3-150M

Files and context on Mac with 24 GB

Each file of GPT-X3-150M (and of GGUF versions the site has analyzed), and how much context fits next to it, with the context cache in 16-bit or 8-bit.

GPT-X3-150M on other hardware

Popular models that run on Mac with 24 GB

Assumes 67% of the Mac's memory is usable (macOS's default limit for the GPU; it can be raised) and at least 4K tokens of context for one conversation, with the context cache in 16-bit unless noted. Fits leaves at least 20% of that memory for context; Tight leaves less.