Salesforce admin can set the order of the related list in page layout. The screenshot below is an example from the Account page.
How can I change Opportunities as the 1st tab instead of Contacts? You can personalize this for yourself.
1. Click your avatar, select Settings
2. Click Display & Layout, then Customize My Pages
3. Select Accounts from dropdown, then click Customize Page button
4. Move Opportunities above Contacts
5. Click the Save button
Now you have personalized your Opportunities in the related list above Contacts, and this does not impact anyone else.