It’s actually dead simple, it just requires a huge investment of resources to get going. We could do it with today’s technology and all we’d need is a ring of mirrors held statically around the sun and reflecting focused light to the sun’s surface. This is probably the least efficient method, but it’s the simplist and most attainable today. A large magnetic loop, held in place as a statite, at either pole would be needed to collect the materials from the resulting solar winds. Strong AI or humans who have become machine intelligences wouldn’t be required, but would certainly help.
Isaac Arthur, one of my favorite YouTubers, has a great episode on Starlifiting. https://youtu.be/pzuHxL5FD5U