For Magento2 how to apply a redirect rewrite in .htaccess file for all URL’s from .html to /

For Magento2 how to apply a rewrite in .htaccess for all URL’s from .html to / URL structure. The M1 store has .html as the end, the new M2 store has / as the URL ending for all products and categories.

We have tried the below:

############################################
## Redirect .html to /
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME}.html -f
RewriteRule ^([^/]+)/$ $1.html

RewriteCond %{THE_REQUEST} ^[A-Z]+ /([^/]+/)*[^.]+.html(?[^ ]*)? HTTP/
RewriteRule ^(([^/]+/)*[^.]+).html$ https://%{HTTP_HOST}/$1 [R=301,L]

RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_URI} !(.[a-zA-Z0-9]{1,5}|/)$ 
RewriteRule (.*)$ https://%{HTTP_HOST}/$1/ [R=301,L]

But it breaks the checkout and some other parts of the site. Any ideas on how to correct please? Looks to be https error on checkout I think.