No, a bowl of oil will not heat up in a microwave by itself. Microwave ovens work by emitting electromagnetic waves that excite water molecules in food, causing them to vibrate and generate heat. Oil does not contain water molecules, so it will not heat up directly in the microwave.
If you want to heat up the oil, you need to place something with water content in the bowl along with the oil, like food or a small cup of water. The water in the food or the cup will absorb the microwave energy and heat up, consequently raising the temperature of the surrounding oil. However, it's crucial to exercise caution when heating oil in a microwave, as it can get very hot and may splatter if not handled properly.