Boltz allows specifying where a ligand should bind.  It is called a "pocket constraint" where you can specify residue numbers in the protein that the ligand should be near.   ChimeraX doesn't have a user interface to set this.  But you could still run a ChimeraX prediction without a pocket constraint, then edit the Boltz .yaml input text file produced by ChimeraX to add the pocket constraint, and rerun Boltz from a terminal.  I described how to do a similar rerunning to add modified protein residues in this mailing list message

The Boltz documentation for specifying a pocket constraint is here

  I plan to add ChimeraX user  interfaces to do these fancier Boltz predictions such as pocket restraints, atom-atom distance restraints, covalently bound ligands, and post-translational modifications, but I haven't done it yet.  There is a reason I have been a bit slow to add those features.  When I have used those capabilities when running Boltz by hand they very often gave bad results.  For example, I had a ligand binding prediction that put the ligand in the wrong place.  So I added a pocket constraint and then it did put the ligand in the right pocket.  But the pose and the binding affinity were all wrong -- I knew because I had an experimental structure.  My suspicion is that if you have to tell Boltz to put the ligand somewhere where it doesn't want to put it, the chance of getting a good pose or affinity prediction is small.  There is a reason why it didn't put the ligand there without the constraint -- it doesn't think the ligand goes there, and forcing it only has a small chance of allowing Boltz to figure out the right binding pose.

Tom