When logged in to the platform, go to settings, by either clicking the wheel you will find in the bottom left corner or your name on the upper right.
Once in Settings go to General > Account & Billing.
There, it’s as easy as pressing the “change plan” button:
A pop-up will appear where you will be able to select the plan of your choice as well as any add-ons you might also want to add.
Once ready, proceed and click on “update subscription”.
Congrats, you’ve now successfully changed your plan!
Note that this option is only available for Admin users.