\bigoslash and \bigominus are large(big) operators of oslash and \ominus, which are available in packages mathabx and MnSymbol.

\bigsqcap is large(big) operator of \sqcap and upside-down \bigsqcup, which is available in packages stmaryrd, mathabx, MnSymbol, txfonts, pxfonts, stix, and fdsymbol.