Can I change from a visit visa to a work visa without leaving the UAE?

Yes — an in-country status change is a genuine, official option in the UAE, so the PRO is not inventing it. The standard route is that the employer obtains a work permit through MOHRE and your status is adjusted through the immigration authority without you leaving the country, against an additional government fee on top of the normal visa costs. Exiting and re-entering is simply the alternative way of activating the new residence, not a legal requirement — your friends are describing how things commonly worked in earlier years. A few cautions before you agree. The change must run through official channels in the employer's name; ask to see the work permit approval and keep copies of everything filed for you. Do not start working until the permit and status change are actually issued — working on a visit visa is a violation for both you and the company, whatever stage the paperwork has reached. And be wary of paying recruitment-related charges yourself, since these are generally the employer's to bear under UAE labour rules. If anything about the arrangement feels informal, having a licensed UAE lawyer glance over the offer and the process is a cheap safeguard against an expensive mistake.