For a "typical" two stage rocket, you will have a very short booster, and little or no gap. Your booster will have pretty big fins relative to the sustainer (required to get the stability margin right, with at least two engines in back--- booster and sustainer--- your CG is pretty far back compared to a single stage.)
With this short booster configuration, at separation your booster section is inherently unstable (a GOOD thing in this situation) and will tumble back to the ground, hopefully with little or no damage. May want to make your fins a bit thicker and fillets a bit stronger than you otherwise might for a single stage. But no specific streamer or chute is required for low power two stage. Definitely needed for High Power and probably advisable for mid power.
If you go for significantly long gap staging
see
https://www.rocketryforum.com/showt...ged-2-successful-flights!&highlight=gap+stage
your booster will still be stable post separation if you do NOT have some sort of recovery device , and it will lawn dart to the ground. This is generally considered non-optimal.
Lots of options to add a recovery device, as seen on the post above, auxilliary pods with engines with non-0 delays will deploy a chute or streamer AFTER separation is initiated by the 0-delay booster motor.
another option is horizontal spin recovery of the booster
https://www.rocketryforum.com/showt...aging-see-last-Post&highlight=horizontal+spin
If you do choose to gap stage (booster/sustainer motors not taped or at least directly butted booster front to sustainer tail/nozzle), you really should have some vent holes or other mechanism to vent the air in the space between motors. Otherwise the air pressure may separate the stages BEFORE the hot gas plume from the booster reaches the nozzle of the sustainer to illuminate and ignite the sustainer. MUST----- NOT-----SAY----PARTICLES............:bangpan:
Good luck, straight trails, and look forward to pics and flight reports.
Tom