i got a ipad mini 2 and it says its up to date with ios 9.3.5.. but im unable to use ebay or youtube i deleted them and try redownloading them but cant

Can you, please, confirm what year and model iPad do you have/own?

The “A” model number can be found on the aluminium back of your iPad, in very small print, right under the larger bold print “iPad” on the back of the iPad.

As described, you are more likely to have an iPad mini1 - not a mini2. It is not uncommon for an iPad mini1 to be misidentified.

Not sure which iPad you have? Identify your iPad model.

iPad mini1 can only be updated to iOS 9.3.5 (WiFi Only models) or iOS 9.3.6 (WiFi & Cellular models).

Apple ended update support for mini1 in September 2016. This model cannot be updated to iOS 10 or later major versions of iOS, as the internal hardware does not meet the minimum technical requirements for new versions of iOS/iPadOS. This limitation cannot be bypassed; the mini1 is a 32-bit architecture device, whilst all recent versions of iOS/iPadOS are designed for 64-bit hardware platforms. The iPad mini1 is obsolete.

The iPad mini2 and mini3 can be updated to iOS 12.5.5. Apple ended major update support for these models of iPad in September 2019 - although they since continue to receive “point” security updates - the most recent being released just a few days go. These 64-bit devices cannot be updated to iPadOS 13 (or any later major versions of iPadOS) as the internal hardware also does not meet the minimum technical requirements (CPU and RAM) for more recent versions of iOS/iPadOS.

Some App developers have dropped support for iOS versions preceding iOS 13.x for technical reasons (often because APIs or software libraries upon which they rely have been updated in the new version of iPadOS, making their App incompatible with earlier versions).  Whilst many App titles remain compatible with your iPad, if you want or need to access to Apps requiring the most recent versions of iOS, you’ll need to consider replacement of your iPad with a newer or current model that supports iPadOS15.

I hope this information provides clarity as to your available options - and the limitations of your iPad mini.