Potentially, but incomers to Cornwall tend to be older people who are more likely to be retired so not work in the town, have a car so not use the local buses, not have kids in the school. Not always, but often.
I'm an incomer in coastal, rural Somerset. I work here but that is rare. Most incomers are retirees. A lot of them really contribute to society and volunteer which is fantastic and people are welcomed, but it is tinged with a downside.
The 'grey migrators' who head West mean an influx of wealthier people who buy the housing young families need. Those people in a few short years get older and contribute less/need more. Houses get 'no cold caller' signs, hand rails go up, the district nurse starts to call.
We have one of the oldest populations in Britain here and not enough carers or staff to keep the local GP surgery and NHS services running full time. The buses don't run in winter. The local school is atpermanent threat of closure.
But this thread is mostly about second homers rather than purely incomers. If you come to work, join in, volunteer, use services then that is contribution. Second homers, in the main, do little of this.