No.
If your iPad is compatible with iPadOS 15,,but it is too far behind in iOS/iPadOS upgrades/updates, you WILL need to use a full Mac with of without iTunes installed or full Windows PC computer with the latest iTunes version installed to do the iPad upgrade to iPadOS 15.
NO options.
Make sure your iPad is, at least, charged to 50% or greater to attempt this.
Also, make sure to do a backup of your iPad's data, prior to upgrading/updating.
Backup to Apple iCloud and/or a full Mac or Windows PC using the same iTunes app OR, if a newer Mac running macOS Catalina, or later, making a backup using the macOS Finder app.
If NO access to a Mac or Windows computer, you will have to seek help from a good friend or family member, with a full Mac or Windows PC, to help you out
OR
Search online to locate and call contact your nearest, “local” Apple Store location to try/attempt to make an appointment to get your Apple iPad upgraded/updated to its latest iPadOS 14.6.
Apple Store employees will be glad to help/assist you.
Best of Luck to You!