The taskbar in Windows 11 is not very configurable, there are very few settings available to adjust it, but there are more improvements coming to the Taskbar in Windows 11, including the ability to move the taskbar in future updates.
If you have a high resolution screen, that may make the taskbar appear very small and if so, either changing the Scale or Resolution on the screen is the only option available.
There is one more setting to check, open the Settings App, then go to Personalization - Taskbar.
Expand the 'Taskbar Behaviours' section.
Ensure this setting is disabled - 'Show smaller taskbar buttons'.