How can I increase RAM capacity in Colab pro+?

To set your notebook preference to use a high-memory runtime, select the Runtime > 'Change runtime type' menu, and then select High-RAM in the Runtime shape dropdown.

Then you can check it by running following code in the cell:

from psutil import virtual_memory
ram_gb = virtual_memory().total / 1e9
print('Your runtime has {:.1f} gigabytes of available RAM\n'.format(ram_gb))

if ram_gb < 20:
  print('Not using a high-RAM runtime')
else:
  print('You are using a high-RAM runtime!')