Changed Permalink and now many broken links and 404s

I’m recently new to wordpress administration (was mainly responsible for simply content creation in my last role). Now I’m responsible for the whole system. The site i’m working on was not originally set up by me and is about 5 years old. The permalink structure was not logical as it was using the month date and really should have been set up for postname. I recently changed the structure to postname and as expected have a number of broken links to deal with (130 to be exact).

What do you recommend as the best approach to handling these 404 page errors and implementing 301 redirects? Do I rewrite the 404 page not found page or is there a plug in?

The content still exists.

example:

https://www.imagesbyberit.com/2010/06/erica-and-billys-wedding-at-the-palace/
has been changed to
https://www.imagesbyberit.com/erica-and-billys-wedding-at-the-palace/

In every case the date has been removed and the post name remains the same.

Thanks in advance.