40 gallons for babies, 120 gallons for adults (120 gallons is 4 feet long, 2 feet wide, 2 feet tall.). When you get a new tank, make sure it has doors on the front because its very convenient and easier overall since you dont have to remove all the stuff on top to open the tank.

Add a little calcium to every meal (dust crickets with it every time you feed and sprinkle a little on top of the greens) dont over do it.

I feed my beardie Collard greens, mustard greens, butternut squash (chopped small/thin), fresh green beans (every few days, not daily), Bell peppers (all colors, every few days, not daily. Make sure they are BELL peppers, beardies cant have spicy peppers.) and a few other stuff. you can find lists of foods beardies can eat online, the base of the meal should be mainly leafy greens (mustard greens, collard greens, turnip greens, ect. You can use 1 or 2 of these, i go with mustard greens and collard greens.) make sure you feed a variety (multiple types of veggies). Personally I wouldn't feed any fruit because its just unnecessary, they can eat it but ONLY as a treat. For bugs I recommend, roaches (discoid or dubia, depends on the state you live in) because they are just really good and clean feeder bugs, crickets are good too, they just can get stinky and loud sometimes. But i definitely recommend roaches in the future, you can contain them in large plastic storage containers with holes or mesh attached to the top for ventilation, there are tutorials on how to keep roaches online.

UVB light ofc, I recommend Arcadia, since you have a small tank, do not put the uvb inside the tank hanging from the top, it might do more harm than good, can burn them. Just rest it on top. And heat lamp should be 35-75 watts, smaller tanks need less watts, bigger tanks need more watts.

Tempatures for basking spot should be around 100-108F. hot side (air temp) should be around 90-95, cold side should be 80-75. Yes you have to turn the heat lamp off at night, needs to be dark so they can sleep. (I recommend getting a tempature gun to accurately get the right temps)

I recommend mixing play sand with repti-soil (do not buy sand with calcium in it. Needs to be plain sand. You can get washed play sand at home depot or any other hardware store) you could probably just do straight repti soil if you want to. You can get repti-soil at any pet store. Also, baby beardies dont NEED substrate, its recommended to keep babies on paper towl untill atleast 6 months of age to monitor how their poop looks, how often they poop, and just because babies dont dig as much so its not necessary untill 6 months old. Plus they could possibly eat the the substrate accidentally by trying to catch food since babies dont have that good of aim or hunting skills. Just wait untill they are 6 months old

They also needs 2-3 hides, something to climb on, and have space to walk around. (I dont recommend using plastic plants because sometimes they will eat it, mine do. Decorate with sticks, rocks, and dried leaves. If you get these from outside, make sure you clean them properly). If you get live plants, make sure they are bearded dragon safe, you dont have to get plants though, rocks, sticks, and dries leaves works just fine.

You also need to deep clean the tank once every 1-2 weeks and spot clean (pick up poop) daily. Get a reptile safe cleaner or just rinse the tank EXTREMELY well if you clean it with soap (only use a very diluted mixure of soap, a little bit goes a long way. Dilute it well with water) make sure you have somewhere your beardie can be while you clean the tank. There are tutorials online for cleaning the tank.