The worst case time complexity of a given algorithm is $ \theta(n^3logn)$ .

Is it possible that the worst time complexity is $ \Omega(n^2)$ ?

Is it possible that the worst time complexity is $ O(n^4)$ ?

The average time complexity is $ O(n^4)$ ?

IMO it is possible as long as you control the constant $ c$ , but then what’s the point of mentioning any other bound than the tight bounds?