Can I find adult websites that were use on my computer years ago

On a Mac, the browsing history limit is dependent on the web browser you are using rather than the operating system itself. Different web browsers have their own settings and configurations for managing browsing history.

For example, in Safari (the default web browser on Mac), you can adjust the settings for how long you want to keep your browsing history. You can choose to keep the history for a specific period, such as the last day, week, month, or you can choose to keep it indefinitely.

Other web browsers like Google Chrome and Mozilla Firefox also provide options to manage browsing history, allowing you to set preferences for how long you want to retain history or clear it entirely.

It's worth noting that regardless of the settings you choose, the browsing history can take up disk space over time. If you're concerned about privacy or want to free up storage, you can periodically clear your browsing history or use private browsing modes that don't save the history in the first place.

No.....unless.....you were using Time Machine to back up the Mac, and you still have all the backups from the past year or two.

Then.....it might be possible to recover the old browsing history from dates in the past. Sounds really complicated and I have not tried this.

You would need to post over in the support forum for the Mac operating system that you are using now for more information on this, since this really has nothing to do with an iPhone.

If you are asking about browsing history on an iPhone, that history is gone if you have cleared the history.