No. If you copy HTML code into memos, the tags are kept as is and not removed. However, if you copy rich text with formatting into memos, the formatting is preserved. In some screens like Projects, the memo toolbar has an option to clear the formatting if you pasted rich text.
There is a global setting in Settings > Time and Expenses - Clear formatting from all time and expense memos- when enabled, CORE removes rich text formatting from all time and expense entry memos. This disables the rich text formatting toolbar on the Time Entries and Expense Entries screens and stores any pasted content as plain text. Existing memos are not modified automatically, but if a memo is edited and saved while this setting is enabled, any existing formatting is removed. When disabled, time and expense entry memos continue to support rich text formatting. This setting does not affect other memo fields in CORE, such as invoice memos, etc.