HI waterwheel most of the builders will be willing to do wider passageways and doorways. at a price of course. Make sure you allow more than the wider width for any sliding doors though. We did our ensuite shower as hobless for wheelchair/shower chair access and made sure the room was larger than a standard esuite so there was plenty of room to manover. You might need cto consider the kind of sink you use to allow the wheelchair to fit slightly under the cabinet. Getting a shower than can be a handshower would be a good move.
We also made the main hallway and main doorways wider for wheelchairs. Just make sure they do the right width. We almost ended up with the wrong width.