Depending how much ‘risk’ you wanna take and knowledge you have about flashing, you don’t need to go back. And always, don’t forget backups
Google provides all images do flash it manually and one necessary step is the new partition table, which should allready be in the custom recovery.
I did my manual update for Pixel 4a from R stable to T dev a couple months ago, when T came out.
Here is the topic from that time: [Walkthrough] Extract eRecovery and boot images using payload-dumper-go - #8 by mihi