I will give you the admit rates from last year based on the UC capped weighted GPA but not specific for Engineering. Under a 4.0 will be a tough admit for Engineering and for these UC’s overall. Going in Undeclared for several of the schools can be problematic if Engineering is your goal. If you do not get a direct admit into the College of Engineering, it can be difficult to switch majors later.
I would definitely first find some safety schools like your local Cal State for instance or UC Merced. Then work on your college list from the bottom up.
2020 Freshman admit rates for UC GPA of 3.80-4.19 capped weighted and not major specific:
2020 UC capped weighted GPA averages along with 25th-75th percentile range:
UCB: 4.22 (4.13-4.30)
UCLA: 4.25 (4.18-4.31)
UCSD: 4.16 (4.04-4.28)
UCSB: 4.15 (4.03-4.27)
UCI: 4.11 (3.96-4.26)
UCD: 4.11 (3.97-4.25)
UCSC: 3.94 (3.71-4.16)
UCR: 3.88 (3.65-4.11)
UCM: 3.68 (3.40-3.96)
Your GPA is within range for some of the UC’s, below the 25th percentile for most and since the UC’s and CSU’s are test blind, the ACT score will not help your chances so they will rely on your GPA and grades in your science and math classes if you are targeting Engineering.
UCSD admits into the University first and then into the major. They do consider alternate majors but changing into Engineering from another non-Engineering major or Undeclared is not guaranteed.
UCI admits similar to UCSD but changing majors can be accomplished by a specific GPA and pre-req courses but not always guaranteed.
UCSB admits directly into the College of Engineering, they do consider your alternate major if it is not an Engineering major but changing into Engineering is not guaranteed.
UCD admits into the College of Engineering, they rarely consider your alternate major and changing majors within the College is easier than from Undeclared or from another College such as Letters and Sciences.
I have seen plenty of applicants with less than 4.0 Capped weighted GPA’s get shut out of the UC’s this year so I would probably concentrate more on the Cal States which also have good Engineering programs.