I would start by searching for hashtags on your client such as #nature and the others.

Then I would try OLAS which is a nostr instagram style client or just browse the media tab of your current client to find nice pictures of nature/art categories.

Then also remember most clients have a global feed, and some for popular in last 24 hours or week. Use those to find big accounts that follow lots of people, then start followimg the accounts they follow and take a look at your feed. Start unfollowing anything you dont care for and within a week yoou will have discovered a lot of cool people.