You are fortunate in that the weather in your area will be in the 70s for the next few days. If you have a nice fairly large pesticide free plant and don't mind sitting outdoors with him, your cham can enjoy a bit of natural sunlight.
Just be sure he is misted enough to stay well hydrated, especially while outdoors.
Whatever you do, don't leave him unattended even for a minute. Chams can and do wander away, get stepped on or get eaten by birds if you are not watching carefully.
He looks like he may be a little younger than a year old.
I believe that the RZilla 25 UVB output is in the right range for a chameleon.
The mistking system is a really good one--your aunt is very kind!
Just be sure things dry out a bit between mistings and don't mist when the lights are out because too much water sitting in the cage, especially overnight, makes for an unhealthy environment.
Here is a link to Sandrachameleon's blog on feeding your feeder insects so they give your cham the most nutrition possible:
https://www.chameleonforums.com/blogs/sandrachameleon/75-feeder-nutrition-gutloading.html
A nice adult size cage will be good for him.
My Jackson's are in 24"x24"x60" cages--they like to wander throughout the cage and will search for insects.
Pay attention to Hoj's advice on Jackson's care in the blog that Pigglett79 added a link for, to give your cham a healthy environment and diet.
Always feel free to ask questions and you can always use the search feature of the forum to look for answers, too.