I am often called out to sites where customers want their Wifi network to reach somewhere it currently can't.
Many of those customers are living semi-rurally on acreage and the distances and places these networks need to go can be great.
I've spoken before about EOP Adapters, they are my preferred solution if properly wired Ethernet cabling cannot be done. They use the existing power circuits in your house as a the network. Of course an obvious limitation is if your house has various circuits - the adapters can't jump circuits e.g. your garage or a new extension will probably be on different circuits.
I am not a fan of Wifi boosters. They've always proven to be flaky and unreliable at best. Their range boosting abilities tend to be fairly limited too.
By far the best way to get your network to extend further is to run cabling.
The best time to do this is as your house is being built.
Obviously that isn't an option for most of us, but if you are building you really should put network cabling in while the house is just a frame. Your electrician on the job should be able to do this for you.
If you are running cabling to an outbuilding I strongly recommend that you run at least 2 network cables.
And, put those cables deep in the ground and very well protected.
I can't tell you the number of times customers have told me they've "run a cable" only to have it fail and/or be irreparably damaged by some subsequent gardening event.
Check your local building rules about running such cabling. But on top of those rules I suggest you DON'T put your network cabling in the same conduits or in close proximity to electrical cabling. There's a chance of interference and in the event of a gardening mishap contacting cables you don't want your network to suddenly be carrying 240 volts.
You'll need to determine how many sockets throughout the site will need to be "live" and factor in a router and switch to cope with that number.
You'll also need to decide on a logical and out-of-the-way location for the cabling to terminate to. For example, if you have 7 rooms that need network sockets, then you'll need somewhere hidden (because these things are ugly) where the 7 cables call all terminate and plug into the central router / switch.
The location will need to be cool, dry and ventilated.
Of course, you don't necessarily need a socket for every device in a room.
A socket can host a wifi access point which can then share the network further.
Obviously as the scale of your house and budget grows this can become quite complex and require quite some forethought and space.
If you are thinking of running a Smart Home, then the planning stage is even more critical so talk to your preferred IT person and your electrician.
You only really get one go at networking a home during building, so carefully consider redundancy and what it is you and FUTURE owners are likely to want to achieve.