With the new RaspiOS (well Bullseye or later), any hdmi_ or overscan options in config.txt are ignored and have no effect.
First you should try what @Thorr69 recommended and use the TV settings to eliminate any post-processing done by the TV itself.
If that has no positive effect, you can try adding the margin_xyz parameters at the end of /boot/firmware/cmdline.txt as described here.
video=HDMI-A-1:margin_left=50,margin_right=50,margin_top=30,margin_bottom=30
NB: the cmdline.txt is just one large line, make sure you add the video parameter at the end of the line and you don't insert any newlines. If your TV is connected to the 2nd HDMI port, replace HDMI-A-1 with HDMI-A-2.