You can create a default team who can access all your opportunities or projects.
For example: If the sales team should be able to see all your opportunities, you can add them as the default team member under opportunities & same for your designers in projects.
To add users as a default team, click on the profile icon on the top right and then on settings.
You can then click on the Add default user button.
Select the user you want to add and then click on “add”.