I bought a loaf of Italian bread that came with plastic wrapping. Not sure if it was made intentional for toasting in the oven. Should I just get rid of plastic and put bread in the oven (I ran out of foil)?
Unless the plastic specifically states that it's ovenproof, do not heat it in the oven.
You can just heat the unwrapped loaf in the oven (I usually do), but it will make the crust crustier. Placing the loaf in a paper bag will reduce this (crusting) effect. The paper bag can be dampened to reduce the effect even further.
For toasting bread, any plastics (except special plastics like roasting foil) or wax papers (except baking paper and related items) are out.
For warming, short answer: No. Long answer: Do not heat plastic items over the temperature they are labelled as safe at - if they are not labelled, assume they will not take more than 70 degrees celsius (compare the chart on https://www.grainger.com/content/qt-types-of-plastics-213 - summary: this is a chart of common plastics; the stated maximum use temperatures of plastics which are marked as food and beverage suitable is 70 or above). Mind that ovens can be inaccurate and that radiated heat transfer from the elements can heat something in an oven slightly above the oven temperature, so an oven could heat the contents well above 70 degrees when dialled to 70 degrees. Mind that warming anything at a temperature below 65 degrees creates a food safety hazard with perishable food.