how do i gain access to my lpcked iphone 8 plus without a computer

If you forgot the passcode for your iPhone, iPad, or iPod touch, or your device is disabled - https://support.apple.com/HT204306

As already stated, you need a computer. Borrow one if you can.

Sadily, there is not a way to regain access to a phone you’ve been locked out from without a computer.

Do you have data on your phone and access to another device (doesn't matter whether it's an iPhone, pc, android, etc)? If you do you can go to icloud.com and log into your account and reset it via Find My iPhone - as long as your passcode disabled iPhone has either data or wifi access this will work!) When you try to log into icloud.com you may get an error message saying that the device you are using cannot access icloud, the solution to this is to go to the browser settings, enable cookies and then request desktop view and once again go to icloud.com and you will be able to log in. After logging into icloud.com go to find my iPhone and if your iPhone has either a data (sim card) or wifi connection you will see your iPhone and have the option to remotely erase your device, click erase your device (ignore the request to add a phone number or message on the screen by clicking next) and in less than 2 minutes your iPhone will be erased and reset to factory default settings. The passcode will be removed and you will be asked to enter your apple id and password after which you can either restore your device via iTunes or icloud if you have a backup or you can keep as a new device and still access everything associated with your icloud/apple id such as previously purchased apps, music, email, pics, contacts, etc.

ℹ This is not the way recommended in apple/icloud support but after I found myself in a similar situation I was able to have my passcode disabled iPhone 5s up and running in under 5 minutes this way!