The Oregon Coast Trail in many places is a road--US 101, with narrow shoulders and lots of RV traffic in summer. About the only way to avoid miles of road walking to detour around the many bays and river mouths would be to take a packraft to cross the river mouths. (paying careful attention to the tidal currents so you aren't swept out to sea). There is also a problem with places to camp, particularly on the northern end, which will force you into motels in a few spots. For example, there is no legal place to camp between Tillamook Head and Nehalem Bay State Park just north of Manzanita, since the state closed the Oswald West campground a few years ago. Beach camping is legal only if completely out of sight of houses (increasingly difficult, unfortunately) and at least 1/4 mile from any state park. The Oregon Coast is more commonly done as a bicycle trip.
That being said, the Oregon State Parks and Recreation Dept. has a series of PDFs with maps and a description of each section of the trail. Here's where to find them:
Oregon Coast Trail Maps You'll also want current tide tables and a watch, because there are many spots that are blocked at high tide.
In some areas of the beach you are restricted to wet sand only (and no dogs) March 15-September 15, the nesting season for the endangered western snowy plover.
OPRD and the Western Snowy Plover