I need suggestions on how to carry 20+ credits in a semester. Please give you idea.
Give up your social life.
Is that even allowed at your school?
At most schools you will probably pay extra for credits over 18 per semester.
So why not take a few classes in the summer?
I would be very careful.
If you end up withdrawing from some classes because it’s too much, you might have SAP problems (completion rate), which could impact future (and current) semester financial aid.
Start out your first semester lower than that. Get a feel for how a normal college workload feels. Add an online class (they don’t have the same finals / completion schedule) if you have extra time. Once you’ve completed your first semester successfully, look at your grades - did you do as well as you’d hoped? If so, add another class the next semester but be careful not to suddenly add on huge amounts of lab or outside hours. Take a class over the summer, that will help the credits to add up more quickly. You CAN do it but you need to drive your courseload based upon what you can handle each semester, not some outsiders judgement of what you should be able to handle. There’s no point in piling on the coursework only to end up with poor grades or a mental breakdown. Build up gradually and be very deliberate and dispassionate in your schedule planning.
It was pretty common to carry >20 credits at my college. We worked our tails off, to be honest - class 9-5 all week & homework all the time (including between classes). It took a lot of self-discipline. Many of my fellow students flunked a class here or there, earning them the privilege of getting to overload even further the next semester. It was brutal. Even my alma mater doesn’t do that anymore. I don’t know that I would recommend it, but I lived through it so do know that it’s possible.
Balance your classes. Don’t take all classes that require papers, or all that have labs. If you can take one online, you might be able to do that class on your own timeline, at 10 pm or at 6 am. Maybe take one physical class (tennis, swimming). Don’t take several literature classes in one semester as you’ll be reading a LOT of books (or get the reading lists before the semester and read over the summer or over break to get ahead).
My daughter’s school allowed up to 19 credits for the ‘full time tuition’ rate but that was because most chem engineers took 18-19 per semester. My D did it only once, and it was a VERY busy semester.
What is your major?
Why do you want to take more than 20 credits?
Don’t bother trying. You will end up withdrawing from some classes.
This isn’t a FA question, but not sure where it should be… 
Why are you considering this. Is this so you can graduate in 3 years?
Often, you will need approval from a Dean or Academic Advisor to take that many credits in a semester. S did this at as a double major.
All the students at my college did this. It’s not easy and requires prioritizing your study habits.