No. If you are given SharePoint Admin rights because you are now in charge of managing the intranet, you need to give yourself access to every site collection individually. If there are hundreds of them, rather ask the IT guys to run a PowerShell script to add you. You can give yourself access to any site collection by selecting the site then clicking Permissions on the ribbon. Stand-alone SharePoint sites display “Manage Admins”. Office 365 group connected SharePoint sites display “Manage group owners”.
PLEASE NOTE! If you have been given these rights, or planning on giving someone these rights, understand that this gives full access to all content on the intranet. You need to act ethically at all times and not share sensitive information. Also understand that every action is tracked, so if you are accessing then electronically sharing things you shouldn’t be, you will be caught. Do the right thing. Take care of your company so your company can take care of you. Make people sign NDA’s for these rights.