Are you looking for an easy way to add a login button to your WordPress header menu? Having a login button on your website can be helpful for your visitors, allowing them to quickly and easily access their accounts. Adding a login button to your WordPress header menu is a great way to make your website more user-friendly.
You can add the Login & Signup block from The Plus Addons for Block Editor, to any page or template like the header.
To check the complete feature overview documentation of The Plus Addons for Block Editor Login & Signup block, click here.
Requirement – This widget is a part of The Plus Addons for Block Editor, make sure its installed & activated to enjoy all its powers.
To do this, open the header template.
Note: You can use the Nexter Builder to create the header.
Then add the block beside your header menu, and go to Forms > Type and select Login or Login & Register.
Then select Button from the Layout section.
This will add a toggle login form button on the header, which users can use to login quickly.

Also, check How to make Custom Password Reset Form Page in WordPress.