Thank you, BeverlyFLADeziner. My concern with the pics you sent is that on the side with the radiators (window side), they could only open ~90* - I'd be wary of having them too close to the radiator in the winter and causing a fire hazard. It also is a pretty inefficient use of space to have them sticking into either the living or dining room since they can't swing all the way open, if that makes sense.

I see 3 possibilities:

One is the typical bi-fold doors, several solid panels, that would be set into a a track in the upper molding, not the floor. When these doors are completely opened, the panels look folded up on both sides of the entry. You might need pairs of 3/4 panels for the width of your entry

2d possibility is to modernize your radiators by using flat wall mounted radiators that could be relocated off the floor and onto the window walls of your dining and/or living room. That would leave you with enough space at both ends of the entry to swing a set of folded up door panels on hinges so they are flush against the wall on either side, inside the dining room or living room, preserving the full width of your entry as is. Hope you get the picture. Here's the type of wall hanging radiator I mean

Last is what might be my bold choice favorite, but it might not really fit the style of your space, and you might not have quite enough room to make it work pleasantly. These are pivot doors

I think they would require some hardware in the floor, and I believe these doors can only be fixed and cannot be pushed sideways to reopen the entry to close to its original width. Not sure if in your space that you have enough swing room combined with comfortable passage room.

We used to have accordion doors when I was a kid.

I keep some hinged dividers (like shoji screens) around the house now for different purposes.

maybe not the aesthetic you are going for, but what about using curtains?

Wrong place for an office.

Any French Doors configuration is going to be $3k+ and IMO that's too much money to spend for a folly.

It's very possible you did originally have french doors there given your layout if those are the original floors--you might be able to tell if someone widened that opening at some point. Our house had french doors separating living and dining (long before our time) and the identical house next door still has them. There are pros and cons. They do take up space, and you need room to fully open them so that they're almost flat when open and the swing doesn't hit anything. You do have room for that, though not if you still want to have a 130" wide opening when the doors are open, and possibly not with your current furniture configuration. You'd have more like a 60" opening, but would be able to close off the space. Tradeoffs. Whether it's worth it or not is going to depend on your own priorities for the space. If you go that route, I'd probably do four panels, with the outer two fixed. I like the idea of trying curtains, too--much less costly.

Provide a drawing of the contiguous spaces with all dimensions, walls, windows all of it. My guess is someone opened the space far more than the original footprint.

To do anything that makes sense would probably mean a closing up of some of that openness......how much? Do a drawing, measure an post it in a comment box. Be prepared to perhaps adjust the layout of furnishings. Otherwise? You won't get the actual possibilities that afford the clearances necessary. Add it to a comment box below, bold and legible in a jpeg format.

Agree with Jan. The opening does look way too wide to be original

Have two stationery doors on either side and then center doors that will lay flat on the stationery ones. This will give you a smaller usable opening, but if you use glass panels will appear large.