Check Engine Light On problems of the 2016 Subaru Impreza Wrx

I purchased a 2016 Subaru wrx (premium) used from a Subaru dealer in albany, NY with under 26k miles for approximately $25k in 2018. On a drive in December 2022 I experienced hesitation and/or stuttering under load or when attempting to accelerate, and car began getting very hot, and close to overheating, and the engine was knocking loudly. After turning engine off and then restarting, the knocking (intensity) was not as noticeable as the initial incident. Initially I replaced all coil over plugs, as cylinder #4 initially was reporting a misfire code after the check engine light came on. This appeared to relieve the misfire briefly, but the issue immediately returned, this time with piston #3 reporting misfires and also exhibiting signs of a possible failed ringland, with oil seeping past rings (on to / in spark plug) causing the engine to run very poorly. Presently upon startup white smoke comes from exhaust out the tailpipe and the engine is hesitating and/or missing, running poorly and I feel it cannot be driven safely with the diminished permormance or complete lack of ability to accelerate normally like a motor vehicle should. I have engaged a mechanic to inspect the engine, but have not yet proceeded with inspection/repairs due to the class action litigation. Current mileage 73563. This car has an fa20 engine.