If you decide to use the expansion bolts I’d recommend renting the giant drill and concrete bit from Home Depot if you can. I installed a deck once and the rental drill made installing the bolts a breeze.

Is it solid concrete, i.e a poured concrete wall, or cinder blocks? If solid, or the cinder blocks are filled, you can use red-head expansion bolts to fix a pressure treated 2x4 to the wall, the another with 3” screws and glue to come out the distance you need. If the cinder blocks are hollow you may be able to stick a 2x4 to it with a ton of pl500 and a few tapcons to hold it until the glue dries.

Edit. PL premium may be better

Andy, from Toy Story, who’s grown up now. He’s allowed to bring one toy and can’t decide between Buzz and Woody, but decides to take Buzz ‘cause, like, he’s an astronaut and all. Well Woody and the gang sneak onboard at the last minute, there’s hijinks, an emergency of some kind, yada yada, everyone gets home safe and sound and important life lessons were learned by all.

Considering that “dark matter” is a thing there’s still something fundamental about the universe that we don’t understand.