It depends on how the space is planned to be used and the size and the configuration.

Do you have a picture of where you are building it??

debra

Here’s the plan for porch including the fireplace

How do you plan to layout furniture in the space? I avoid wide entries into a living space, it can limit furniture placement.

Generally your furniture placement is limited to inside the rectangle, and every thing outside the rectangle is circulation space.

Your inspiration photo seems like a bad idea (maybe even against code?) if you plan a working fireplace. You have to have a non-combustible material a certain distance in front of the firebox, whether raised or at ground level.

Is it a gas FP or wood burning?

I love sitting on our hearth or putting my feet up to warm my tootsies so I vote raised.