URL length does not have much impact on how Googlebot crawls.
Changing your URLs will have the biggest effect. Googlebot will forever come back and crawl your old URLs. You will need to implement redirects to the new URLs and maintain those redirects indefinitely. If you change all your URLs, this can significantly increase the number of URLs that Googlebot needs to crawl. It does not usually mean that Googlebot crawls fewer of your page URLs. The redirect requests are so small and fast that they don't usually take away from your crawl budget much.