I like using BC847C and BC857C myself (SOT23-3 = TO-236AB), as I can simulate them well using ngspice and they're dirt cheap (3-5€ for 100 at Mouser).
If you want a specific adapter board, say a 3-pin or 2×3-pin adapter for breadboard use with the PCB
vertical, i.e. pins parallel to the PCB, straddling it, just design them and manufacture them at JLCPCB, PCBWay, et cetera! I like designing them at EasyEDA, because it works in the browser (does require a network connection), and is really easy for a hobbyist type like myself for this kind of stuff; KiCAD is free and local and at least as good, but with slightly steeper learning curve (in my opinion). At JLCPCB, one hundred 1"×1" boards costs you about 10€ + shipping. So, we're talking about 30€-40€ investment for 100 NPN and 100 PNP BJT adapter boards.
SOT23-3 have typically limited maximum current and power dissipation, but there are many SMD packages with much better thermal and current characteristics. Soldering those can be annoying, so you can use the assembly services to have the PCB manufacturer also assemble the boards (except for the pin headers, which you likely have to solder yourself by hand). For breadboard use, use the backside as a (flat) heat sink with plenty of vias to the cooling pad of the transistor package, and consider using thermal adhesive to glue a small heatsink (those used for Raspberry Pi's and other small chips, typically 8×8mm to 12×12mm, height varies) on the back side. It will be in electrical contact with the transistor cooling pad, but the thermal properties are pretty darn good.
There are a few tricks. One is to do iterative development, and start with sets of five, and see if it can be improved before ordering a larger set.
Soldering pin headers parallel to the PCB works better, if you strengthen them with vias, especially vias-in-pad. (The pad will of course be rectangular, about 1mm wide, at 2.54mm spacing.) In my opinion, a zig-zag pattern of vias on each pin (at each edge of the pad) will strenghten the connection, so that one can push and pull the adapter to/from a breadboard from the PCB itself. You might want to have the sides an indentation in the middle, for better finger grip. You might add a polyfuse to limit current, depending on the use cases.
If
I can do it, anyone can.