No seu mapa de teclas de texto sublime, adicione:
{ "keys": ["ctrl+1"], "command": "fold_by_level", "args": {"level": 1} },
{ "keys": ["ctrl+2"], "command": "fold_by_level", "args": {"level": 2} },
{ "keys": ["ctrl+3"], "command": "fold_by_level", "args": {"level": 3} },
{ "keys": ["ctrl+4"], "command": "fold_by_level", "args": {"level": 4} },
{ "keys": ["ctrl+5"], "command": "fold_by_level", "args": {"level": 5} },
{ "keys": ["ctrl+6"], "command": "fold_by_level", "args": {"level": 6} },
{ "keys": ["ctrl+7"], "command": "fold_by_level", "args": {"level": 7} },
{ "keys": ["ctrl+8"], "command": "fold_by_level", "args": {"level": 8} },
{ "keys": ["ctrl+9"], "command": "fold_by_level", "args": {"level": 9} },
O nível 1 é dobrar tudo. Combine o "," no seu JSON para funcionar. Feito. ;)