Change aspect ratio of mockup picture frame size

We are looking for a skilled graphic designer to modify our existing wall frame mockup. The task involves adjusting the current frame design from a 3:1 aspect ratio to a 3:2 aspect ratio. The ideal candidate will have experience in graphic design and a keen eye for detail to ensure that the mockup maintains its visual appeal after the adjustment. Please include your portfolio showcasing similar work when applying.

Please let me know the cost and how long it would take?