Is there a RAW way to allow the PCs to recover only some ...
Every class needs to long rest to replenish their spell slots, except for Warlocks — their special thing is that they get their spell slots back after short rests and long rests.
Warlock 5.5e Build Guide | 2024 D&D Class Overview | Arcane Eye
Short Rest Spell Slots: Pact Magic recharges spell slots quickly.
Oathbreaker Paladin/Warlock Multi-Class Build in Baldur's Gate ...
The Death Knight - Oathbreaker Paladin Warlock Multi-Class Build in Baldur's Gate 3 copy ... This tactic involves using your Warlock spell slots, which recharge on a short rest, to fuel your Divine Smites.
How do warlock spell slots work in 5E?
Warlocks regain all spell slots on a short or long rest, and they can swap one spell and one cantrip when they gain a Warlock level.