'Restore' can have many different meanings. Please post a picture of your bench so what we can see what you are starting with an how it is damaged.

You could paint it

You can have it powder coated to a permanent hard finish.

Wrought iron would typically need to be stripped of the paint, wire brushed free of the rust and then primed & painted with enamel (oil based) paint.

The rod iron just needs a good wire brushing and a coat of tremclad

Hello could you possibly post a photograph to better see your situation and area of concern?

Having a visual might be helpful to be able to offer the best guidance .....to a help find the best suggestions or potential solution for your Refurbish project.

Here's a tutorial for how to restore rod iron that might help: https://www.lahabrafence.com/blog/5-easy-steps-to-restore-your-rusty-wrought-iron-fence

it would be nice to have a picture of your bench to help yo out

YES powder coat it if you are referring to getting the finish restored. We did this for our front porch rod iron bench and it turned out amazing. Look in your yellow pages where they will do this. Otherwise, if you are referring to more restoration involving rod iron parts....check out this post:

https://www.hometalk.com/38046991/cast-iron-bench-restoration-before-after

Before and After Cast Iron Bench Restoration

Excellent info here:

https://www.hometalk.com/27212723/q-old-iron-wood-bench#!

I have seen powder coated metal last a very long time. Mom had custom-built powder coated wrought iron railing made for her front patio and 15 years later, it still looks great!