Minisplits come in all sorts of sizes, find some model numbers of multi-zone units and then go to
AHRI Certification Directory, scroll down the list to find variable speed mini-split and multi-split heat pumps and you can compare the efficiency ratings.
Smaller single head mini-splits will get you the best efficiency and larger ones and multi-split units a little bit less efficiency but it is still very good for what you are getting.
Since you built the house, you know how well insulated it is, it would be a good idea to do a load calculation to know the required BTU output so you can properly size the unit for cooling. If you are going to use it for heat, you'll want to make some decisions there regarding sizing to accommodate that too. In my case I want to size for cooling and use a smaller unit than what could heat my house in an extremely cold Minnesota winter but I plan to keep my natural gas furnace anyway and natural gas is extremely cheap where I live in comparison to even the most efficient mini-splits and the balance point on cost is around the freezing point, oddly enough that is also roughly the point where the unit is running full capacity on heating too so if I use it for heating, I would still be in decent shape for sizing. I'm also undersizing my mini-split consideration with plans to use the central air that I already have if it ever gets too hot but I'm also planning on putting in 90% solar blocking screen over my large sun facing windows through the summer and I think that will make a 12k mini-split into the appropriate size for my house and weather conditions in my area for nearly any temperature. I learned from the 6th Manual J book that I found cheap on ebay to calculate everything and I've done a whole bunch of going through the latest manual J book at the reference only(can't check it out) section of the main branch of the library in my county to be sure that my heating needs could be met with the smallest furnace I can install but I'm not willing to heat with a mini-split getting that cold, too many compromises to the size of system I'd need to install and the detriment to cooling EER and SEER in the summer.