Chemically Peculiar (CP) stars are intermediate-mass stars in the main-sequence phase that exhibit anomalous surface abundances as a result of atomic diffusion. Their stable atmospheres, slow rotation, magnetic fields, pulsations, and binarity make them valuable laboratories for studying stellar structure and evolution. In this thesis, we present our results from investigating CP candidates in the Nainital–Cape (NC) survey and the intermediate-age open cluster NGC 2126 using ground- and space-based observations. We identified a magnetic Ap star from the NC survey that shows indirect evidence that its magnetic and rotational axes are nearly orthogonal, based on TESS photometry and Doppler Imaging. High-resolution spectroscopic analyses of three NC survey δ Scuti CP candidates revealed that they do not exhibit any strong CP characteristics, and seismic modelling was performed to constrain their stellar parameters. In NGC 2126, we established the pulsating eclipsing binary V551 Aur as a cluster member using Gaia astrometry and confirmed a pulsating CP star through spectroscopic observations from LAMOST. These results highlight the diversity of CP-star phenomena and demonstrate the importance of spectroscopic confirmation in distinguishing genuine CP stars from photometric candidates. The thesis also highlights the advantages of high-precision space photometry and spectroscopy for identifying and characterising CP stars in both field and cluster environments, providing novel insights into the interplay between magnetic fields, diffusion, and stellar variability.