Your comment is correct. However this value is max. torque value not nominal value.
If your engine is 10 kg-cm, we can simply say:
$$F = m * a$$
$$F = 10 kg * 9.80665 m/s^2$$
$$F = 98.0665 N$$
This value indicates the maximum force you can apply.
If we examine the torque and forces simply:
$$τ = r * F$$
If the distance increases, the force value to be applied decreases, so the load on the motor decreases. It is theoretically true that there is a linear relationship here. In practice, it tries to approach this line, but this is directly related to your engine quality.
In general, it would be more correct to give the following answer. You can also tow a load that you connect directly to the shaft of the motor. However, it may not be correct to use it at maximum torque for this. It doesn't mean it don't work, but the longer you stay at maximum torque, the more you can damage the motor itself or the gears. Therefore, I think that staying 10 percent below the specified value is sufficient as an operating range. Of course, we cannot verify this without the engine's datasheet.