The first thing you should take into account is that Instagram is a visual content-oriented social network, which means that the only types of posts allowed are Image and Video (Reels). You can add up to 10 images per post for Business accounts, and single-image posts only for Personal ones.
For the same reason, they limit the number of hashtags and characters you can add to your posts. Currently, you can add up to 30 hashtags and your post's text can only have up to 2200 characters (including the hashtags).
Keep in mind that Postcron limits the number of posts you can post to Instagram Personal accounts to 140 per day, and 25 per day on Business Instagram accounts.
Sum up
Text Posts: No
Max. characters: 2200
Hashtag Limit: 30
Image Posts: Yes
Multi-Image Posts: Yes (Business accounts)
Link Posts: No
Video Posts: Yes (Reels and Stories)
Mentions: Yes