People who do not have an Instagram account may still need to access Instagram to view photos. For example, photos of some events you are a part of are only uploaded to Instagram and there is no other way to see them.
How to see Instagram without an account! (2023)
While there is no way to view and browse Instagram without logging into an account, you can use third-party web apps and search to view public profiles on Instagram.
You can only see public profiles, as well as tagged photos on Instagram without an account, but you can see private profiles. If you don't have a profile and you want to look at someone's Instagram photos or see their stories, you can use the search function as well as various third-party apps available to view profiles without registering or logging in.
If you want to scroll through Instagram and see things like photos, likes, or comments, you can, but you wouldn't be able to engage with any posts because you don't have an account yourself.