I havent used this option but from my settings.js file the default is commented out and is defined as an object. So im guessing
httpServerOptions: { limit: '25mb' },
no need for app.use or anything else .. i think it should apply for all middleware
[EDIT]
I see there is also an option in settings for //apiMaxLength: '5mb',
The maximum size of HTTP request that will be accepted by the runtime api. Default: 5mb