This study is a Phase Ib/II clinical study. It includes two stages: Phase Ib and Phase II. In the Phase Ib stage, the primary objective is to evaluate the safety and tolerability of SYS6006 in combination with Enlonstobart Injection in participants with advanced solid tumors, and to provide a basis for dose selection in later clinical studies. The primary objective of the Phase II stage is to assess efficacy and safety of SYS6006 in combination with Enlonstobart Injection in participants with advanced solid tumors.