LocalOptics supports the four Google Business Profile post types. They share most fields; what differs is the extra information each type requires.
Standard
A general update. It needs only a summary (your post text), plus an optional image and call-to-action button.
Event
Announces something happening on set dates. On top of the shared fields, an Event needs:
Event title (required by Google).
Start date and end date (required). Google rejects an Event without both.
Start and end time (optional).
Offer
A promotion or coupon. On top of the shared fields, an Offer needs a title and dates, plus optional promo details:
Offer title and start/end dates (required).
Coupon code (optional).
Redemption URL (optional), where customers claim the offer.
Terms and conditions (optional).
Alert
A time-sensitive announcement (Google has historically used these for situations like COVID-19 updates). Availability depends on what Google currently allows for the listing.
Fields every post shares
Summary - the post body. Google allows up to 1,500 characters.
Call-to-action button (optional) - pick a button type (for example Learn more, Call, or Order) and the URL it opens.
Image (optional) - Google suggests 720x540; keep files under 4 MB.
Spintax and variables - vary text across locations. See Spintax & Dynamic Variables.
Previous Post URL - insert the previous post's link to daisy-chain posts together.
Scheduling - publish now or schedule for later; scheduled posts sit in the location's Posts list until they go live.
Never put a phone number in the post body - Google may reject it as phone stuffing. See Why Google Rejects Your Posts.