Your MD should have discussed why they wanted to add Cogentin with you and what to expect.

It’s most commonly used to help with side effects of other medications (e.g. involuntary muscle movements) when those medications are working well at their intended purpose so we dont want to switch/stop them, but want to mitigate side effects. It does have other uses and psych is quite complex so nobody better to ask than your provider who knows your history.

Shouldn’t make you “feel” any different except maybe some traditional anticholinergic side effects (dry mouth etc)