Looks like you dont have Site collection administrator rights on your site collection. If you have full control on the site collection then you can see access request option by going >
site settings > User and permissions > Access Requests and Invitations.
easy workaround, I think, 1st you need to fix your permission. Ask your administrators / owner of the sites, added your id into site collection administrator group. this will put you back on old level where you can do everything.
for access request, read this support article from MSFT