Outlook can be configured to open web links in Microsoft Edge even if Chrome, Firefox or another browser is set as your default browser in Windows.
You can change this from within Outlook.
Classic Outlook
Open Outlook and go to File > Options > Advanced.
Scroll down to File and browser preferences.
Find:
Open hyperlinks from Outlook in
Change the setting from Microsoft Edge to Default Browser.
Click OK to save the change.
Links opened from Outlook should now use your normal Windows default browser.
New Outlook
Open Outlook and select Settings.
Go to General > Files and links.
Find:
Open hyperlinks from Outlook in
Change the setting to use your Default Browser.
Links clicked in Outlook should now open in the browser you have configured as the Windows default.
What This Change Does
This setting only changes which browser Outlook uses when opening web links.
It does not change your Windows default browser.