If you carry the right Allen wrench, yes
There is a big golden arrow printed on the hatch that says "RESCUE". It points to a hole. Around the hole are instructions for opening the hatch. It even shows you which direction to turn! (Source: Apollo Program Summary Report page 4-32)
More details about the hole:
The exterior input is a socket in a recessed shaft, which penetrates the command module hatch and is rotated by a removable hand tool. It is used for ground operations, for checkout and test, for extravehicular activities, and for postlanding rescue. Because it is exposed to and must survive reentry heating, it is protected by a beryllium copper heat sink and is thermally insulated from the cabin interior by glass fabric spacers.
You need a 7/16 inch Allen (hex) wrench that is at least 4.25 inches long.
The hatch also can be opened from the outside by a tool that is part of the crew's tool set and is carried by ground personnel. The tool is the emergency wrench, essentially a modified allenhead
L-wrench. It is 6-1/4 inches long and has a 4-1/4-inch drive shaft.
One of these tools had been stowed in the lunar module, but that won't help us now. The 6.25 inch dimension appears to be enough to provide sufficient leverage, yet small enough to be stowed in the LM. As long as you can get enough leverage, your tool doesn't need that. The 4.25 inches is the depth of the hole; your tool could be longer. The socket is 7/16 inch, but I suppose a slightly smaller metric tool could work.
Crank away and the hatch will unlock.
You have no idea how many pictures I found of actor Richard Hatch, who played Apollo on Battlestar Galactica!