Structural engineer time. In short... it depends. In our case where we opened up about 24' that used to be the rear wall of our 1 story house there was a column needed due to a point load, a pier and footer added below the column to take the load to the ground, and four LVLs (meeting in the column / side by side) as headers. Both ends of the opening were above existing piers that were deemed to be of more than adequate strength so they were left alone. Then of course there were the materials and fasteners used to make the connections. That said, it took the framers one day to remove the old wall and frame in the new opening, but I already removed all of the drywall, electrical and plumbing ahead of time.

This is a rather meaningless guess without actually seeing the plans... but it’s the internet, what can go wrong? 16 inch deep floor truss spaced at 24 inches on center (On Center is dist from center of floor joist to center of next adjacent floor beam or joist). Double top chord bearing... Top chord is more or less the flanges or the top part of a beam (top flange, vs bottom flange, or the web... i.e. parts of a beam) or the top element in a truss. Double top chord is something I associate more with steel beam and poured concrete deck construction than with wood residential framing construction... generally means two different layers of top chords ( in a truss or joist), or top flanges (in a web-flange beam cross section). Someone would have to see the detail to interpret geometry more specifically. Top chord bearing typically means the truss or beam is supported by the underside of the top chord, instead of the bottom of the beam sitting on top of (or “bearing” on) what is beneath... Plan reading 101: These notes are about the floor system... if the ends of the above floor’s joists or trusses are supported by the framing in the wall you want to remove... (i.e. floor joists supporting the floor above are perpendicular instead of parallel to the wall you want to remove) then that wall is supporting the load of those floor joists (and the contributing area’s floor load from above floor), and you will need to replace the removed wall with a strong beam or truss for all these floor joist ends to bear on with the wall removed. Note that the replacement beam would span from one place where there is a column or vertical structure that will support the load of the above floor to another (from hardpoint to hardpoint)... length of the beam, and demolition to install the beam would therefore likely be greater than the 5 ft you seek to remove. Random guesses... without eyes actuallyon your plans.... Joe’s point that there’s the plans... and then there is investigating how it was really built/framed on site is also non-trivial

What is the span that you need to open? You may be more limited in the span you can open or the remaining header. With an all brick construction house, with two floors above our kitchen. We have had a structural engineer draw up how to open the kitchen into the current refrigerator room (which is built like an enclosed porch). It will be a lot of steel for a relatively short span with at least a foot remaining in the ceiling for a header. Part of it has to do with keeping the house from falling down while the put it in, but i have not seen it done yet (or received the updated quote for the steel after the structural engineer made the drawings). We got a quote that had an allowance for the beam construction, then paid a structural engineer to evaluate and make the drawings and we are waiting to figure out how close the allowance was to the estimate.

Hire a General Contractor on a consulting basis, with the provision that they will get first crack at your envisioned job that’s bound up with removing the wall. Bear in mind that supporting a load bearing wall is only a small part of removing that wall. Walls contain things. They provide backing for furniture arrangements, and art, and lighting controls, and electrical outlets. People rarely think all of that through well on the front end unless they have an interior designer on board. This is a ”give a mouse a cookie” situation, with tons of downstream consequences and costs other than your direct ask.