Heat gun and a suction cup for a plastic bumper. For steel, it's unlikely you're going to be able to pull it out because bumper steel is too thick. If you're pulling out sheet metal like door skins and fenders, then get an Amazon PDR kit with various pulling tools and tabs. Then buy quality PDR glue from a PDR supply company and go watch some youtube videos.
Be very careful with the heat gun as you can overdo it and brown the paint. If that happens then you'll need to wet sand, buff with a compound, and finish with a polish. Not something I'd recommend without experience. You need heat in the metal to make it more malleable, but not so much that it makes the PDR glue tacky. After the glue hardens completely, use the tools to pull the glue tab and sometimes pull the dent out. Do not try this if the paint is broken, you'll pull the paint off of the panel in the shaped of the glue.
If you live in an area with a professional PDR shop, just take it there.