My friends who go to CSU/CC and had a sub 3.0 GPA in HS all have 3.8+ GPAs in CSU/CC; you’ll be fine.
If you’re talking about transferring from UC to UC then it’s a slightly different process. There is no TAG for intra UC transferring. Having a 3.0+ GPA as an Econ major at UCSC/UCR shouldn’t be too hard if you put in the time.