I don’t think it really matters where the new hire comes from. It would be a plus if it is within the same company because that only means there is room to grow and be promoted. However, experience is absolutely necessary for the position. If you are within the same company, you might be familiar with the procedures the company follows, nevertheless, it is important to be very knowledgeable on how to perform your job in broad terms so you can be reliable for the team you are working with.

I think that there are benefits to hiring both in the company and from outside the company for a project team. Hiring from with in the company provides the project manager with someone who is familiar with the company culture and processes.  In addition, hiring with in the company will provide the project team with internal candidates who are motivated and committed to the company's goals. These internal candidate will also require less time to adapt and not require any sort of training to get accustomed to company ways. Internal hiring also demonstrates the ability to grow and develop with in the company. On the other hand, hiring from outside the company can bring fresh perspectives, new ideas, and diverse experiences to the project team. External candidates may also bring specific skills and expertise that are not currently present within the company. This can be particularly beneficial for projects that require specialized knowledge or experience, or that involve working with external partners or stakeholders. Overall, the decision of a project manager to hire from with in the company or source outside the company is not a simple task and requires many factors to make a final decision.

As @kaf43 there are benefits to either side of whether one decides to hire project managers within the company or externally. I also agree with @vv48 and how it does not necessarily matter where the project manager is hired from, as long as they are equipped with the skills and the experience to successfully lead a team to completion for the project based off the requirements for it. If the company hires internally it allows for their employees to grow professionally within the company making them more helpful and valuable for the company (the company may not have to pay as high of a salary for an internal hire compared to an external hire). Additionally, internal hires would be beneficial for the team as the individual being hired would already be familiar with the company culture, values, goals, and procedures which would all be helpful in their transition from a team member to a project manager. On the other hand, external hiring could bring in new skills, perspective, techniques, experiences etc. that may not be present in the current company's work environment. This different background could help enhance the project by bringing in new innovative ideas that may not have been seen by an internal hire. Overall, I think that the particular project would drive the decision of whether to hire a PM internally or externally based on the projects demands and vision.