Can a DC motor 3V can hold not so heavy objects?

I want to buy cheaper DC motors for my robotic arm but i don't know if 3V DC motor can carry and hold not so heavy objects? if not what kind of dc motor should i buy?

While it is true you will use less power with a motor that has a lot of gears, you sacrifice speed. No free lunch.

Any dc motor is fine. With a small motor, you need to use gears to increase the power. A larger motor will draw extra power from your batteries so you are better off using a lower power motor with gears

It is easier to use motors like 7V to 12V which are closer to the supplies you should be using.These can be more efficient than the el-cheapo toy motors represented by 3V motors generally. The rpm of 3V motors and other small motors is generally very high. You will need gears to make the speed more appropriate. Once the speed exceeds about 5000 rpm the gears become more of a problem.

What is used to move an arm lifting a weight is power, in watts. This relates to how quickly the particular weight is lifted against gravity. This comes down to mechanical power = force x distance / time.
The mechanical output power of motor is derived the same way, and is proportional to rpm * torque.

The mechanical power is related to the electrical power required. It depends on the mechanical load and motor efficiency. Electrical power is volts x amps. The battery needs to be able to deliver the current in amps that the motor uses to move the load at that voltage and so speed. With higher voltage motors this current is less, so the losses are reduced.

A good source of motors with gears for a small robot arm are old battery electric screwdrivers and battery electric drills. You will know the voltage to use from the battery they have. This battery is also a power source that can supply the significant current required at times. The maximum allowed continuous current is more difficult to determine, but is something like: