It’s rare (though not unheard of) for an agent to read a client’s book very quickly and offer almost immediately. But if you’re an unpublished author writing fiction and an agent is offering to represent you without reading the full book, RUN. and if you’re querying agents who then offer representation contingent upon using “editing” or “book packaging” services they charge for, RUN.
(Also, basic research of any agent you query should help you avoid even getting approached by people like this.)
There are a lot of scams out there and one of their nastiest tricks is making you think you’re an exceptional writer worthy of extraordinary offers outside what you hear is typical. They’ll pretend the “services” are standard and they’ll lean on your inexperience to dupe you while dangling praise and promises in front of your starry eyes.
Agents will not charge you for their services until they’ve sold a book for you (and that fee will be taken out of your earnings, not paid by you directly). Agents will not refer you to paid editing or packaging services and they do not offer on fiction projects by new authors without reading the whole book. And agents will not try to convince you to sign with them by promising you’ll be a bestseller or, in general, talking like an advertisement.
Read that “contract.” And listen to your more experienced friends who are trying to protect you.