Can any blockchain hold blobs and more importantly how much it will cost? For example I know the Stellar blockchain can hold a small amount of text content cal

Can any blockchain hold blobs and more importantly how much it will cost? For example I know the Stellar blockchain can hold a small amount of text content called "memo" when making a transaction, but not sure if the "memo" field can be used _after_ a transaction is made. Probably it is a public field that can be read by anyone? I was always wondering what if we start putting content into a blockchain in general.