  In Kagome metal CsV$_3$Sb$_5$, multiple intertwined orders are accompanied by
both electronic and structural instabilities. These exotic orders have
attracted much recent attention, but their origins remain elusive. The newly
discovered CsTi$_3$Bi$_5$ is a Ti-based Kagome metal to parallel CsV$_3$Sb$_5$.
Here, we report angle-resolved photoemission experiments and first-principles
calculations on pristine and Cs-doped CsTi$_3$Bi$_5$ samples. Our results
reveal that the van Hove singularity (vHS) in CsTi$_3$Bi$_5$ can be tuned in a
large energy range without structural instability, different from that in
CsV$_3$Sb$_5$. As such, CsTi$_3$Bi$_5$ provides a complementary platform to
disentangle and investigate the electronic instability with a tunable vHS in
Kagome metals.
