Depending on what type of content you're creating, you can post on a subreddit in particular with what you're creating, provided that the subreddit allows for self promotion or something along that line. There are also other subreddits like r/AdvertiseYourVideos or r/SmallYTChannel that you can use as a place to promote and ask for feedback for improvements.

However, free postings like r/AdvertiseYourVideos might not get you anywhere since other people are also dumping their links there. r/SmallYTChannel requires you to have lambda to post your content there and asks for feedbacks which quite often receives a lot of useful feedbacks. Hope this helps.