Here is an easy way to find keywords.
1) Run the top 4-5 competitors through SEMrush.
2) Click on ranking keywords
3) Export the keywords into a spreadsheet or text file. You can filter by many metrics. I use search volume.
4) Bulk run them through a program like keywsearch.co
5) Anything under a score of 30 is pretty easy to rank (there are many variables, like age/authority of a website, but generally, this is a good rule)
6) Use the list to build out target pages.