For Lightroom, I reckon m3pro will be fine.
Base model comes with 16gb RAM and a 512gb SSD.
I'd suggest that you special-order with a 1tb SSD.
REASON WHY:
The 512gb SSD is not "slow", but... the 1tb SSD is fully TWICE as fast (due to internal memory chip arrangements).
The faster SSD will make any operations that "hit" the drive (such as caching) faster, also.