Hashtags give Instagram context about your content. So 1-2 relevant hashtags are better than none (or hundreds). Creating your own hashtag is also a no-no.
Bear in mind a lot of people follow specific hashtags like they follow accounts. A random hashtag stunts your chances of being favoured by the algorithm. Relevant trending hashtags have a higher reach, which bodes well for you.
Socials Sorted: “I do my hashtag research monthly. I create a document with [my clients’] 5 pillars and find hashtags for those pillars which are niche applicable. But I’ve told my clients to only use niche hashtags appropriate to the content they are posting e.g. fitness (they use ones I give them).”