Septic tank Final Connection

[G3_DIY]

Hello fellow plumbers....building a new house and having to make final connection of whole house trunk line to new septic tank and need some assistance....I'm knocking out inlet plug but not sure how far in to extend 4" line. There's a 4 1/2" cement square just inside the tank. Is that where the waste dumps into the tank? Sure is a small space for solids to empty into tank..one person suggested cutting end of pipe at 45° angle facing down so less chance of clogging. Another suggested gluing a clean out "T" to end of inlet pipe inside tank for future clean out access once tank buried. As you can see, getting alot of "local advice".. Any professional guidance /assistance much appreciated.