The paint buildup hides the profile in your first picture. Cut the end off clean so we may see.

Often, there is not a single bit that will create a profile. Sometimes you need to use several, and a router table, because the board may need to lay flat on the table for some cuts, and standing up against the fence for others.

If you have a Rockler or a Woodcraft store locally, they can probably help if you take a cutoff to them.

How much do you need? Have you checked local lumber yards for a source?

Moldings are often stock profiles. Lots of charts available via search.

https://www.google.com/search?sca_esv=ed31745f76a805c8&sxsrf=AE3TifPShI9Qgn0sf6cFhtPQqJZ4PmW7Zw:1752763830582&q=baseboard+profile+chart&udm=2&fbs=AIIjpHxU7SXXniUZfeShr2fp4giZ1Y6MJ25_tmWITc7uy4KIeioyp3OhN11EY0n5qfq-zENwnGygERInUV_0g0XKeHGJEwefEKJ1XNp8V3tgIFOgML-dUH9j4VGQfY_QTVhRbeKsmHwnQKaexE8IMLJqjtL_ZwBjXX7Z87sul29qhw_sJvQ1-n9E1vmu6l1xI_-VsrM3qoUyNF1sMqVpbxDdeHV-pQy_QQ&sa=X&ved=2ahUKEwiN3PyLksSOAxWCJe8CHX8IDdIQtKgLKAF6BAgTEAE&biw=1382&bih=997&dpr=1.27

I don't need much, just enough to do the dining room and part of the kitchen where the cabinets aren't covering, like 50 feet at the most.

I've seen that profile in homes far less than 100 years old so you should be able to buy it at a trim shop.

It is crazy how much detail goes into making up a profile. Trace the end of it so you have a good drawing of the profile and take it to a local lumber yard. If they don't have it you may have to either have a skilled carpenter add different trim pieces to build a matching trim profile, or pay to have a (blade? can't remember the word) made specifically for your cut. Go to a lumber yard that has been around for a long time.

Go to a real lumberyard and look at 5 1/4" Band Base. I think that will match pretty dam close. Stay out of the box stores.

Close but not an exact match is fine if you are using in the entirety of a room. Nobody will notice slight change from room to room.

I had to match 170 year old trim in just parts of a room. Now that was a PITA!

If you have an actual millwork shop in your area they might be able to help you if the real lumberyard can't. I agree that this looks like something that you could match pretty closely with a couple different router bit passes. Here's an example of the kind of place I'm talking about: https://www.andersonmcquaid.com/profiles/

For small quantities, like you're looking for, a woodworker with a shaper with an insert cutter head could grind your exact profile on a knife and run the molding for you. I agree that for a whole room it only needs to look the same from a short distance, not be exactly the same.