Unconditional outbound routing for a single extension?

Here’s another question that bothers me.

Setup: FreePBX14. 3 trunks, 12 extensions.

10 extensions use different outbound routes and trunks (prefix-based routing).
2 extensions have to use only one trunk regardless of what they dial and how they dial - i.e. extension 201 has to be routed into Trunk 1, while extension 202 has to use Trunk 2 unconditionally.

What is the best way to make this work?
Thanks for your insights.

Use the “Caller ID” field on the outbound route is a simple way.

If you don’t like that, you can add dialed prefixes for the extensions so they bore sight on one trunk or another.

You mean ‘prepend’, so that prepended digits would automatically go into the trunk that would then strip those before actually dialling out?

Yes.
Or use the commercial COS module or as Cynjut was suggesting: