I've been led to understand by watching videos & reading etc that inverters can operate at 133% of their rated value, so 5kw = max 6.65kw.
Others have covered it but you can have more PV power connected to an inverter's solar PV inputs than the inverter's rated AC power output. How much more is a function of the inverter's specifications and local installation codes.
133% is a pretty nice DC:AC power ratio as others have explained, providing more power over longer period of the day and better performance in cloudy/low light conditions or when arrays are split over different azimuths or tilts, or are just not facing in an optimal direction for maximal energy generation.
This assumes the array(s) is (are) not overly impacted by shading. No point adding extra panels if they are just going to be in the shade most of the time.
The most important piece of advice when it comes to home solar/battery system installation is to choose your installer wisely. Due your due diligence on them. Good installers will go through a decent appraisal of your home's energy needs, as well as understand what future changes may need to be considered. They will have been in the business for a long time and have a good reputation for the standard of their work and post sales support, as well as understanding the specific installation issues in your local area. They will also use their own staff for the installation rather than sub-contract it out.
In some cases homes add electrical energy demand by getting off fossil fuel sources (gas, petrol/diesel). Having a system designed with any future changes in mind is helpful. Changing it later is usually a PITA.
It is advantageous to have an EV charging solution which integrates with the solar/battery system. This means it can be programmed to charge in a manner that best suits you, be it on a schedule, or from excess solar energy, or when grid energy is cheap, and to avoid draining the home battery to charge the EV etc.
That said, if your EV energy demand is low and likely to remain so, then you can probably manage it fairly well manually.
The V2X uses the DC connection in the MG4 CCS2 socket, so they can certainly do V2X.
While the MG4 (and frankly most EVs nowadays) are capable of working with V2X, the issue comes down to what impact using it has on your car's warranty.
I don't know about MG in the UK but in MG Australia have made no statement about potential warranty impacts of using V2X. They are clearly reserving judgement on that and I guess it's a get out of jail free card for them. The same applies to most of the EV manufacturers, with a few exception for specific models. They are just not fully on board yet.
The tech in my case (Sigenergy EVDC charging module) clearly works as I have tested it with both our MG4 (2023 64 Essence) and MG ZSEV (2023 Excite) but I have no intention of using our cars for regular V2X duty. For us that functionality is for the scenario of an extended (multi-day) grid outage and even then only in case we need some supplemental energy to support the home battery and solar PV system (e.g. a run of very poor solar production days).
